Chapter 5

bluestar forensic

a chemical used to make blood otherwise invisible to the naked eye visible via luminescene

automated fingerprint identification system (AFIS)

a database that contains fingerprints collected from various known sources; it is used to identify unknown fingerprints

mitochondrial DNA (mtDNA)

a form of DNA inherited from ones biological mother only

nuclear DNA

a form of DNA unique to an individual

friction ridge analysis

a formal name for fingerprint analysis; it involves the examination of the ridge structures of fingers (or hands or feet)

Rapid DNA

a fully automated process whereby a DNA profile can quickly and relatively cheaply be developed from a buccal swab taken from a subject

national integrated ballistic information network (NIBIN)

a national database operated by the ATF that contains bullet and cartridge's casing images and is designed to link bullets/casings fired from the same gun

combined DNA index System (CODIS)

a national database operated by the FBI that contains DNA profiles collected from various sources; it is used to identify offenders based on their DNA profiles.

next generation identification (NGI)

a national fingerprint and biometric database operated by the FBI

crime scene

a place where the crime occurred or where evidence may be located

DNA sweep

a tactic that involves the collection of DNA from people who could have committed the crime in question and comparing these DNA profiles to the DNA of the perpetrator that was recovered from the crime scene or victim.

arriving at the scene: initial response/prioritization of efforts

- 1. when arriving at a crime scene, the initial responding officer should be thinking about protecting the scene as well as the safety of himself or herself, other officers, and citizens. the officer should approach the crime scene cautiously and be aware of any persons or vehicles in the area or leaving the area that may be related to the crime. The officer should make sure that it is safe to enter the crime scene to take further action. It is important that the officer remain alert and attentive when approaching and processing the scene. - 2. a determination has to be made about the legality of entering and searching the crime scene. Recall from ch. 4 that there is NOT a crime scene exception to the search warrant requirement. A search requires a warrant or must be justified by an exception to the search warrant requirement (consent, plain view, exigent circumstances). If an exception does not apply, a search warrant must be obtained. - 3. Officers should be constantly mindful of possible threats to their safety, including hazardous materials, chemical threats, and dangerous persons. If such threats are apparent, appropriate assistance must be requested. - 4. after neutralizing dangerous persons or other threats, the officers next responsibility is to provide or summon necessary medical attention for injured parties. A common issue at crime scenes is that medical personnel unknowingly or unintentionally alter the scene. Officers should ensure that medical personnel have guided access to the scene but that they minimize contact with evidence. if resources allow or if the victim is in grave danger of dying, an officer should accompany the victim to the medical facility to document any comments made (a dying declaration) and to preserve evidence. - 5. the crime scene must continuously be protected from persons at or near the scene. Only authorized personnel and individuals essential to the investigation should be allowed to enter the scene. Some crime scenes can be emotional places where relatives of the victim may understandably have little regard for the integrity and security of the crime scene. Bystanders, concerned citizens, and media representatives must also be prevented from affecting the crime scene. In addition, suspects and witnesses must be identified and separated. Information may be compromised when witnesses are allowed to share with each other their versions of events prior to being interviewed. - 6. officers must establish the boundaries of the crime scene in order to protect it. Effective barriers can be established with crime scene tape and/or barricades. The boundaries should encompass where the crime actually occurred, paths of entry and exit of the suspects, and places where the victim/evidence may have been moved or discarded. The perimeter should be as large as possible. A crime scene sign in sheet can be a useful tool to document the presence of authorized personnel at the scene. this sheet should be started as soon as practical after the boundaries of the scene have been established. No unauthorized persons, including citizens or media, should be allowed to enter or alter the crime scene. persons who are at a crime scene when boundaries are established should be removed from the scene. persons with access to the scene must not alter the scene in any way (not use the bathroom, open windows, adjust the thermostat, touch anything unnecessarily, etc.) Suspect actions should be closely controlled (not wash hands, change clothes, use bathroom, etc) - 7. whenever appropriate the initial responding officers should brief the investigators taking charge of the investigation. Witnesses and what they have said should be reported, physical evidence should be noted, and progress on other investigative activities should be relayed. These actions provide critical continuity during the initial phases of the investigation. Communication regarding activities, responsibilities and duties, and evidence is extremely important. - 8. all activities and observations of the responding officers should be recorded in the required reports as soon as possible. This documentation must include descriptive information about the crime and the crime scene and information obtained from witnesses, victims, suspects, and other individuals at the scene.

the collection of DNA

- DNA evidence may be collected from the crime scene, the victim, the suspected perpetrator, or other places depending on the particulars of the investigation. Extraordinary caution must always be exercised when collecting DNA-analyzable evidence for at least two reasons: 1. the biological material may contain potentially hazardous pathogens (human immunodeficiency virus, hepatitis, covid-19) that can cause disease and 2. because samples containing DNA can be easily contaminated. Contamination could happen if someone sneezes, coughs, or even talks over the evidence, or if someone simply touches the evidence without taking sterile precautions. - when DNA is collected from a suspect for comparison (or reference) purposes, it most often involves the use of a buccal (oral) swab. A sterile cotton swab must be used for this purpose. The inside surfaces of the cheeks should be rubbed thoroughly with the swab, and the swab should then be air dried and placed in a paper sleeve or an envelope with sealed corners. swabs from different people should be packaged separately. the samples do not need to be refrigerated. Other, less desirable but potential reference samples can be obtained from surgical samples, pulled teeth, an item of clothing worn only by the individual of interest, or another other item with which the individual has direct contact. - when transporting or storing evidence that may contain DNA, the evidence must be kept dry. The evidence should be stored in paper bags or envelopes. Evidence that may contain DNA should never be placed or otherwise stored in plastic bags because plastic will retain moisture that may damage the DNA. direct sunlight and warmer conditions can also damage DNA evidence. Staples should not be used to secure evidence bags because an accidental injury from a staple might lead to contamination of the evidence. Of course, the chain of custody must be maintained. The chain of custody would likely include the following individuals: the person who collected the particular piece of evidence and began the chain of custody, the person who transported the evidence to the police department or crime lab, the person who logged the evidence into the evidence room or the person who received the evidence at the lab, and the person who received the evidence from the lab for final inventory.

The applications of DNA in criminal Investigations: DNA Phenotyping

- DNA phenotyping involves using DNA to obtain information about the donors facial characteristics, such as hair color, eye color, face shape, skin tone, and the presence of freckles. This information can be used to create an approximate facial image of the perpetrator. Although this technique is still evolving, it has already been used in nearly 150 cases nationwide. Caution must prevail here, however, as the process is subject to error and is, at best, just a prediction about the characteristics of the perpetrator. Private companies such as parabon Nano labs and universities are at the forefront in developing and applying this emerging technology. This information that results from the phenotyping process is not allowed as evidence in court.

The applications of DNA in criminal Investigations: DNA sweeps

- a DNA sweep, sometimes known as a DNA dragnet, involves collecting DNA from people who could have committed the crime in question and comparing these DNA profiles to the DNA of the perpetrator that was recovered from the crime scene or victim. The first investigative use of DNA occurred in England in 1987 and involved a DNA sweep. In this case DNA was collected from several thousand men who lived in the area where two murders and rapes had occurred. After it was discovered that a man named colin pitchfork had avoided providing a DNA sample by having someone else pose as him, the investigation focused on pitchfork. Eventually he was identified as the perpetrator and charged with the crimes. - although DNA sweeps are still sometimes used in investigations, the serious legal and logistical issues involved in collecting DNA from a group of people make this tactic a last option. To collect DNA from subjects depends entirely on their consent and cooperation. Further, the tactic is usually only feasible when investigators believe that the perpetrator lives in a geographic area in which few people reside. However, in a recent case from the Netherlands, investigators attempted to collect DNA from 20,000 men who lived in the area in which the homicide occurred. The killer turned out to be one of the 6,000 men who avoided providing a DNA sample.

Biological evidence and DNA: saliva

- although human saliva is mostly water, it also contains mucus, proteins, and enzymes as well as other substances, such as epithelial cells and white blood cells. DNA analysis is performed on the epithelial cells and white blood cells. In a criminal investigation, saliva may be most likely to be found on cigarette butts, bite marks, bottles, can, chewing gum, clothing, and envelopes and stamps. Saliva is a good source of DNA and can be the subject of DNA analysis procedures. - saliva can be easily overlooked as it is usually invisible to the naked eye, although it may become visible under an alternative light source. As with semen, there are chemical tests that can be used to identify it. In the case of saliva, such tests detect analyze, an enzyme found in high concentrations in saliva. However, the test is not definitive because other types of tissue and bodily fluid also contain amylase. - the collection and packaging of saliva is the same as with semen. In liquid form it should be collected via a clean cotton cloth or swab and air dried. If possible, entire saliva stained objects should be collected. If it is not possible to collect the object that contains the saliva or to cut out the saliva sample, the saliva stain may be collected by using a cotton swab moistened with distilled water. A control sample of an area close to the saliva should also be collected using the same distilled water and type of swab used to collect the evidence. All items should be packaged in paper envelopes or bags, not plastic. The control sample should be packaged separately. Care must be taken that metal or glass items are not frozen. For long term storage, dried saliva should be refrigerated or frozen.

the basics, DNA

- it is found in virtually every cell in the human body, and its structure is the same in every cell. Except for identical twins, no two people have the same DNA (the same nuclear DNA to be exact). The DNA in a persons saliva is the same as the DNA in his or her hair, skin cells, and blood. Because of its absolute uniqueness and individual characteristics, human cells and the DNA contained in these cells can be a valuable form of evidence in criminal investigations. DNA can be easily and unknowingly be left by perpetrators at crime scenes and with victims, and this DNA can then be compared to the DNA obtained from a particular suspect. DNA can be found in numerous types of biological substances, each of which could constitute evidence in an investigation. These biological substances include blood, semen, saliva, vaginal secretions, skin cells, hair, perspiration, urine, feces, and vomit. However, the most frequently encountered types of biological evidence are blood, semen, saliva, and hair. - The result of DNA analysis is a DNA profile that shows a persons DNA characteristics. A DNA profile can be compared across samples. DNA analysis was first used in a criminal investigation by Dr. Alec. J. Jeffreys in England to identify a person who murdered and raped two girls. It was also used the first time in the US in 1987, in a criminal case during which a Florida jury convicted tommy lee Andrews of rape. - DNA is individualistic evidence, therefore DNA analysis may be used to associate positively and absolutely a perpetrator to a crime scene, to the victim, or to tools used in the crime. Similarly, DNA analysis can be used to eliminate positively and absolutely a person from consideration as a suspect. As such, it would be inaccurate to consider DNA analysis only a tool of the prosecution that is used to convict suspects. DNA analysis is a powerful tool of justice- a tool that can be used to identify and convict the guilty and to free the innocent. - DNA can also be used to confirm the identity of victims or the remains of victims when a complete body is not found. In cases such as this, a DNA sample may be taken from hair recovered from the victims hairbrush or from skin cells recovered from the victims toothbrush or clothing and then compared with the remains. Another possibility is to compare the DNA from relatives with the DNA of the body or remains.

Physical evidence information

- can establish that a crime occurred (corpus delicti evidence), can help establish the elements of a crime or assist investigators in determining whether a crime actually occurred. - can be used to make associations between crime scenes, offenders, victims, and instruments (tools). forensic evidence collected during criminal investigations is used most often to establish associations. - Additionally, in helping to establish the elements of a crime or in making associations between offenders, victims, and so fourth, physical evidence can function as corroborative evidence and thereby support other evidence that establishes an issue in question. EX. physical evidence such as pry marks can support a victims statement about a burglary having occurred. - Certain forms of physical evidence may serve an identification function. EX: dental evidence (x-rays) can be used to determine the identity of an individual (usually a dead body) as can DNA evidence and fingerprints. - physical evidence can act as direct or circumstantial evidence. EX: simpson case; Simpson's blood drops at the crime scene were direct evidence that he was at the crime scene. The fact that Simpson's blood was found at the murder scene was also used to infer that simpson committed the murders. - it is not effective at initially identifying a culprit when one is not already known. Certain forms of forensic evidence (DNA) can lead to a culprit being identified or the crime being solved, but in the grand scheme of things this is still a relatively uncommon occurrence. - physical evidence does not play a role in every case, some cases are solved by eye witnesses and confessions. - is continuing to become more and more important and influential in the criminal investigation process. Especially true with DNA analysis, which has been of tremendous value in some criminal investigations and still has much potential yet to be realized.

Measurements of crime scenes and the placement of evidence should be included. The diagram should include the following

- date, time, and location - weather and lighting conditions - identification and assignment of personnel - dimensions of rooms, furniture, doors, and windows - distances between objects, persons, bodies, entrances, and exits - measurements showing the location of evidence - a key, legend, compass orientation, scale, scale disclaimer ("dimensions are not to scale") or some combintaion of these features

other types of forensic evidence: bite marks and dental evidence

- dental evidence can take two primary forms: dental identification and bite marks. In both these instances, the fact that each individual has a unique set of teeth in terms of form, arrangement, dental work, and bite pattern can make dental evidence a potentially valuable form of evidence. The physical characteristics of bite marks and dental identification typically consist of the distance between teeth, the shape of the mouth/bite, teeth alignment, teeth shape, missing teeth, and wear patterns of the teeth. A primary means of identifying decomposed dead bodies is dental identification, during which dental radiographs of the individual are compared with those of the dead body. a match may be made on the basis of a comparison. of course, this manner of identification is only possible if the decedent is suspected to be a particular individual and x-ray records are available for comparison. - bite marks can be either offensive or defensive. offensive bite marks are left on a victim by a perpetrator; defensive bite marks are left on a perpetrator by the victim. Bite marks may also be an area from which DNA (saliva) can be recovered. if a victim bit an offender, DNA may also be recovered from skin tissue in the victims mouth and teeth. Bite marks are seen most often in cases of homicide, sexual assault, and child abuse. There are several methods of collecting bite mark evidence from victims and suspect biters: photographs, dental casts, clear overlays, computer enhancement, and electron microscopy. However, bite marks on the skin will change in appearance over time, which may affect the ability to accurately link a bite to a particular suspect. The difficulties and likely errors in attempting to link a suspect to a bite means bite marks should not be used as individualized evidence. In fact, the analysis of bite mark patterns has been so fraught with error that some states have recommended such evidence not be allowed in court.

other types of forensic evidence: fibers

- every type of fabric or textile material contains fibers. natural fibers include, for example, wool, cotton, glass, and fur. Synthetic, or man-made, fibers include nylon and polyester, among others. Fibers from one source are easily transferred to other surfaces, such as the transfer of fiber to fiber (clothing to clothing), fiber to skin, fiber to shoes, fiber to vehicle. Examinations of fiber evidence can vary in sophistication. EX: a comparison can be made between two fibers based on a relatively simple microscopic examination of the color, diameter, and other distinguishing characteristics of the fibers. A more precise examination may be made between fibers based on color through the use of microspectrophotometry. This procedure essentially involves shining light on a fiber and recording the absorption of that light. Chromatography can be used to identify the chemicals used to make the dye of the fiber and comparisons can be made on this basis. However, even using the most sophisticated methods, fibers cannot be individualized to one particular source. - fiber evidence is most often found in homicides, assaults, and hit and run offenses, and it may be found on clothing, skin, shoes, and carpeting, among other places. Fibers should be packaged in paper envelopes with sealed corners. when possible, the entire garment or textile should be submitted for analysis

Biological evidence and DNA: hair

- hair is most likely to be found in homicides and assauilts, especially when some struggle between the victim and the perpetrator took place, and in hit-and-run cases that involve a person. Hair may also be found on the clothing of victims and perpetrators, in and on vehicles, and on personal items, as well as in places such as the clothes dryer lint trap, washing machines, and sinks. - hair consists of an outer core of overlapping cells known as the cuticle, the cortex (which contains the pigment of the hair), and the medulla (an inner layer of cells). hair also contains a root, which can be of great use in the scientific analysis of the hair. Significant variation in hair structure is often found within the same individual, particularly in hair from different places on the body (head, face, pubic area). As a result of this, a range of samples must be analyzed when comparing the structure of the hair. Through the relatively simple microscopic examination of a hair shaft, it is possible to draw several conclusions about the hair: whether it is from a human or an animal (and if it is from an animal, what type of animal), the race of the individual, the body area from which the hair came, the method of removal, color and form (straight, curly), and whether the hair was damaged or altered (dyed or bleached). Chemical examination of the hair may reveal the presence of contaminants in the hair and may identify ingested drugs and how long ago those drugs were ingested. DNA analysis is most often performed on the root of a hair. Non-DNA analysis of hair is unable to positively associate hair to a specific individual, but it may be useful in excluding certain persons as the source of the hair. - hair should be dry before being packaged into paper envelopes with sealed corners. Hair should be carefully collected with clean tweezers to prevent damage to the hair root. In collecting comparison samples, at least twenty-five to fifty hairs from different parts of the head (or pubic area) should be obtained. Hairs should be combed and pulled out and collected by a trained medical professional.

fingernail scrapings, skin cells, and touch DNA

- it is standard practice to protect and collect tissue from the fingernail scrapping's of victims of violent crimes. If contact occurred between the victim and the perpetrator in a violent interaction, skin, blood, and/or hair may be recovered from under the fingernails of the victim. These substances can undergo DNA analysis and play a central role in an investigation. Medical personnel (medical examiners in the case of homicides) are typically responsible for collecting this evidence. When dealing with homicides, investigators should protect the hands of the victim with sterile paper bags until such time as the evidence can be collected. - the amount of biological sample necessary to conduct a DNA analysis has gotten smaller and smaller overtime, to the point that today the substance need not even be visible. Such is the case with touch DNA. touch DNA involves the recovery of DNA from very small samples of skin cells left on an object or surface as the result of simply touching it. although touch DNA is a major development in the capabilities of DNA analysis, it is not without its drawbacks. First, since the skin cells cannot be seen, it takes an educated guess to find them. Second, with more sensitive DNA testing comes a greater potential for contamination during collection and analysis. Third, secondary transfer is more likely to occur with touch DNA, and, as a result, there may be an increased risk of false conclusions. A secondary transfer of DNA occurs when DNA is transferred between objects or persons via another person or object. EX: if two people shake hands and on of these people then touches a gun, both of their DNA could be recovered from the weapon, thus leading to incorrect conclusions about who actually touched the weapon and is the perpetrator. Such mistakes have been uncovered in actual investigations and have led to convictions being overturned. - the collection of skin cells should be performed with a sterile, cotton-tipped applicator (Swab) wetted but not saturated with one drop of sterile water from a sterile dispenser. The area where skin cells are suspected should be swabbed with the entire surface of the swab. The swab should then be air dried and placed in a sterile paper enclosure.

other types of forensic evidence: paint

- paint is a pigmented polymer applied and adhered to various surfaces. paint evidence may be found when paint has been trasnferred from one surface to another, either as wet paint or chips from dried paint. PG 120

the crime scene and its management

- physical evidence often begins its role in criminal investigations with its discovery and collection at the crime scene. - EX: in a homicide several places may be related to the crime and may contain evidence associated with the crime: the place where the victim was encountered, the place where the victim was first attacked, the place where the murder occurred, the place where the body was discovered, and the place where the murder weapon was disposed of. Sometimes investigators make a distinction between primary and secondary crime scenes. In the Simpson case, the house of Nicole brown Simpson was the primary crime scene; OJ Simpsons house was a secondary crime scene. Because secondary incorrectly suggest a less important crime scene and/or evidence, it is essential to understand that crimes may have multiple scenes, each potentially containing critical evidence. - crime scenes commonly include residences, businesses, streets, yards, parking lots, vehicles, and hospitals. Regardless of its location and how it may be classified, a crime scene needs to be managed and controlled in order to preserve evidence and to ensure its integrity. Since critical evidence may be found at crime scenes, critical errors in the investigation may also occur there. - not all crime scenes are equal in their value to investigators. Some crime scenes may be more valuable than others because only certain people have access to particular places. Some crime scenes contain little evidence, whereas some contain a wealth of it. Accordingly, appropriate and necessary crime scene procedures vary considerably from crime to crime. In addition, resources and the policies of particular police departments may also dictate the proper course of action in crime scene investigations. Searching for and collecting physical evidence from crime scene is not an inexpensive endeavor; it takes time and money. As a result, although relatively little time may be spent processing burglary crime scenes, much time is likely to be spent at homicide scenes. The basic guidelines discussed here are ones that should typically be followed by investigative personnel in preserving and recovering physical evidence in major crime investigations such as homicides.

The applications of DNA in criminal Investigations: rapid DNA

- rapid DNA refers to a fully automated process whereby a DNA profile can be quickly and relatively cheaply developed from a buccal swab taken from a subject via consent. Whereas traditional DNA analysis is done at a crime lab where it may take weeks or months to get results, rapid DNA is performed at a police station and the results can be obtained in less than two hours. The rapid DNA profile is produced by an easy to operate machine; the cost of this machine varies from $30,000 to $150,000 depending on the model. The cartridge required to analyze each sample costs $100 to $150. The machine is designed to only analyze buccal swabs from people because DNA from crime scenes is more complicated to analyze. - due to the emerging nature of this technology and corresponding questions about its reliability, rapid DNA results are typically not allowed to be entered into or searched in the FBI CODIS system except under certain circumstances. Rather, individual police departments and counties have developed their own DNA data banks to store samples. While rapid DNA solves one problem- the delay in obtaining a DNA profile from a crime lab- a serious issues remains: if Rapid DNA profiles cannot be used in CODIS and if crime scene profiles are not in the individual police department data banks, then investigators will be unable to easily search for a link between a rapid DNA profile obtained from a suspect and a DNA profile obtained from a crime scene. When concerns about the accuracy of Rapid DNA results are addressed and offender Rapid DNA profiles can be routinely entered into CODIS, then this new technology may have a major impact on criminal identification.

other types of forensic evidence: shoeprints, impressions, and tire tracks

- shoeprints are created when material from the bottom of shoes, such as blood or mud, is transferred to another surface, leaving an outline of the bottom of the shoe. Shoe impressions and tire tracks are most often left in soft material such as mud or snow, and they reveal the outline of the shoe or tire. shoeprints and impressions may reveal the perpetrators entrance to and exit from the crime scene and movements around the crime scene. It is also possible to determine from an analysis of the shoeprint or impression certain class characteristics, such a the size of the shoe and the make and brand of the shoe. tire tracks may reveal the direction of travel, the size and manufacturer of the tires, and possibly the make and model of the vehicle. - well worn shoes may show wear patterns and other wear elements that make the shoe distinct. However, even with seemingly unique wear patterns, there is no scientific agreement about the number of individual characteristics needed to make a positive association. - prints, impressions, and tracks should first be photographed and then, if possible, a cast of the impression or track should be made. If the impression or print is left in soil or mud, the recovery procedure involves pouring dental stone (a variant of the type of gypsum used to make dentures) into the impression. When the stone hardens, the mold reveals the outline of the impression. If the track or impression is in snow, the snow is first sprayed with a special wax to harden the impression and then the dental stone may be used.

other types of forensic evidence: soil

- soil consist of organic natural materials such as rock, minerals, and decomposing plants, and it may also contain man made materials such as brick, concrete, glass, or paint. Examination of the color, texture, and composition of soils may allow for an assessment of whether the soils share a common origin. One of the most common scientific techniques of analyzing soil is the density gradient tube. In this procedure the densities of soil samples are analyzed via chemicals that separate the particles comprising the soil. If the pattern of separation is similar in two or more samples, it indicates soil was consistent properties. Once again, despite using the best methods, soil cannot be individualized to one particular source. - soil evidence is most likely to be found on the bottom of shoes, in places where shoes may leave soil (floors of vehicles, hard surface walkways), on clothing, and on the tires, fenders, and body of vehicles. It is recommended that when soil samples are to be collected, they be taken as soon as possible. in addition, if it is present, soil should be collected from the immediate crime scene area and from the apparent entrances and exits of the crime scene. samples should be collected from wherever there is a noticeable change in the color or composition of the soil. It is often necessary to collect numerous soil samples from a scene. a map should be drawn showing from where soil samples were taken. investigators should not remove soil from recovered shoes, clothing, or tools. paper bags should be used to package materials containing soil, and soil samples should be placed in plastic, film type canisters

other types of forensic evidence: fingerprints pt2

- the automated fingerprint identification system (AFIS) has made fingerprints more useful in identifying perpetrators. With an AFIS in place, whenever a person is fingerprinted by the police in that jurisdiction due to being arrested, applying for a particular job or for some other reason, those fingerprints are entered and stored in the AFIS. then, after a fingerprint is collected from a crime scene, it is scanned into the AFIS and the computer searches the system, looking for prints with similar characteristics. The newest systems on the market today can search hundreds of thousands of prints within minutes; older systems require hours to search the same number of prints. The system may identify several prints that are the most similar in their pattern and unique characteristics. the print in question must then be manually compared with the "hit" print by a fingerprint examiner. It is in this manner that fingerprints recovered from a crime scene may lead to the identity of a perpetrator. - prior to AFIS technology, fingerprints were used in several different ways. First, when a fingerprint was recovered from a crime scene, it was simply filed away until a suspect was identified in some other way, and then a comparison of that suspects prints and the recovered prints was made. Second, if a suspect was already identified, a comparison could be conducted immediately. third, a manual search could be made through the fingerprints on file in that particular jurisdiction or on file with the FBI. the process resembled trying to find a needle in a haystack, and rarely was it productive. - although the use of an AFIS makes the processing of fingerprints much more efficient, there are several limitations to the technology. First, the collection and analysis of fingerprints from potentially thousands of crime scenes can be costly. Second, a multimillion-dollar AFIS can be foiled by a pair of $0.59 latex gloves. That is even if the perpetrators prints are in the system because of a previous arrest, and AFIS may not be of any use if the perpetrator is careful enough to not leave fingerprints. An AFIS may be able to compare glove prints, but the precision of these comparisons may be much less than with fingerprints. third, even if a perfectly clear fingerprint is collected from a crime scene, the perpetrators print will not be identified if her or his prints are not in the system being searched. Some states and police departments operate their own AFIS systems. The drawback is that only the fingerprints collected in the jurisdiction are contained in that system, if they are actually even entered. Thus, if a perpetrators prints are held in one AFIS but are recovered by a police department in another jurisdiction, an identification would not be made. - to improve the effectiveness of AFIS technology, in 1999 the FBI deployed a national fingerprint data base known as the integrated automated fingerprint identification system (IAFIS). in 2014 this system was fully replaced with the next generation identification (NGI) system. Along with more than a hundred million fingerprints, this system also stores other biometric data, including photos, tattoos, scars/marks, and palm prints. Data in the system are provided by federal, state, and local law enforcement agencies from across the country and can be accessed by these agencies in their search for perpetrators. This expands dramatically the number of fingerprints taken.

The applications of DNA in criminal Investigations: combined DNA index system (CODIS)

- the combined DNA index system is a current database operated by the FBI that allows federal, state, and local crime laboratories to share and search DNA profiles electronically. All states have access to CODIS. Contained in the CODIS database are DNA profiles of known offenders (those arrested and or convicted; known as the offender index) and DNA profiles of unidentified offenders collected from crime scenes and or victims (the forensic index) - crime laboratory analysts enter the DNA profiles obtained from crime scene evidence into CODIS and the system scans the offender index for a match. If there is a hit, investigators can obtain a search warrant authorizing the collection of a reference sample from the identified person. The laboratory can then compare the crime scene DNA with the identified persons reference sample DNA. However, if the perpetrators DNA is not in the system, a match will not be obtained. In this case the culprit will have to be identified in some other way. CODIS can also be used to search DNA recovered from other crime scenes (the forensic index) in an attempt to link crimes together. - as of the end of 2019, the offender index of CODIS contained the DNA profiles of nearly eighteen million individuals convicted of or arrested for crimes as well as almost one million DNA profiles collected as a result of there investigations. CODIS has assisted in approximately 485,000 investigations.

other types of forensic evidence: fingerprints

- the early foundation of forensic science rested on the principle that each person has a unique pattern on his or her fingers. this principle is still valid, and fingerprints are still potentially valuable evidence in criminal investigations. Fingerprints consist of ridges, depressions (hills and valleys), and separations (where ridge lines end or split). Fingerprints remain unchanged and consistent throughout ones lifetime. The fingerprint on each finger is unique. Fingerprints can be useful because perpetrators can leave them on items and at crime scenes. - fingerprints can be broadly classified on the basis of the pattern of ridges that comprise the print. These patterns are classified as loops (ulnar loop, radial loop), whorls (plain whorls, double loops, central pocket loops, accidental loops), and arches (plain arch, tented arch). The most common type of fingerprint is the loops pattern (approximately 66% of the population have loop prints), followed by whorls (approximately 33%). Only about one person in twenty has prints that resemble arches. - fingerprints taken as a result of the fingerprinting process ("being fingerprinted") are usually recorded on a ten print fingerprint card either through the use of ink or the digital capture of prints. On the card the prints are arranged as a double row in a particular sequence. - the analysis of fingerprints (as well as sole and palm prints) is known as friction ridge analysis, and it consists of comparisons of the impressions left by the ridge structures of ingers (or hands or feet). friction ridge analysis is a means by which individualization can be determined, although this is highly dependent on the quality of the print, among other factors. There are three conclusions that may result from a comparison of fingerprints: individualization (or identification), exclusion, or inconclusive. An identification (or individualization) is made when prints from two different sources could not have produced impressions with the same degree of agreement in ridges features. It is important to understand that in contrast to DNA matches, this is a subjective assessment as there are no statistics by which to identify the probabilities of a match based on population distributions of certain friction ridge features. Exclusion is made when prints show observable differences in ridges. An inconclusive conclusion is appropriately drawn when similarities and differences in prints are not able to be determined. - fingerprints recovered from a crime scene generally fall into one of three categories: 1. visible transferred prints, such as when ink, blood, or some other visible liquid material is transferred from the fingertip to another surface, 2. visible impression prints, which occur when the print is left in a soft or sticky material, such as wet paint, clay, or putty, and 3. Latent prints, the most common type, which are made when oil and perspiration naturally present on fingertips are transferred to another surface but are invisible until developed through various techniques. DNA may also be obtained from fingerprints. The most common techniques used to recover latent prints consist of the application of powders, chemicals, and glue fumes. Although chemicals can be useful for identifying latent prints, they can affect DNA analyses. "dusting" for prints involves the brush application of a fine powder to surfaces believed to potentially contain latent prints. The powder adheres to the oil and perspiration transferred from fingers and makes the prints visible. This technique is most likely to reveal prints when the surface is hard, smooth, and nonabsorbent, such as glass, painted wood, or metal. Powder of a different color can be applied to provide contrast with the surface being dusted. Fluorescent powder can also be used in a similar manner to enhance the visibility of latent prints. One-sided sticky tape is then pressed onto the print and lifted, revealing the print. The tape is then pressed onto clean card stock paper to save the print. - chemical methods can be used to recover prints from soft or more porous surfaces, such as paper or clothing. Various types of chemicals can be applied either by spraying the surface, through a process of fuming, or by dipping the object containing prints into a chemical solution. Another technique involves glue (or cyanoacrylate) fuming. With this methods the object being examined for prints is either placed in a sealed tank and then exposed to the vaporized cyanoacrylate, which adheres to the print and makes it visible, or the fumes are applied via a fuming wand. - laser technology has also been used for highlighting latent prints on difficult surfaces. regardless of the method used to recover prints, the visible prints first should be photographed and then "lifted" by placing adhesive tape over the print so that the powder adheres to the tape. The tape is then placed on a card that provides contrast with the lifted print, thereby preserving the print and mkaing it visible for further analyses and comparison. Clean gloves and single-use brushes should always be used when collecting prints. Photographs of the powdered print should be taken before its lifted. - locating quality latent prints is not an easy task and depends on the crime scene. Obviously places, such as door handles, phones, drinking cups, and weapons, as well as less obvious places, such as toilet handles, should be examined for prints. Many recovered prints are of poor quality, making them nearly worthless as evidence. Fingerprints can be smeared or can become dirty, or the fingerprint themselves could have been dirty, all of which could obscure the individual characteristics of the fingerprints. - if fingerprints are recovered from a crime scene, elimination prints may need to be taken. Elimination prints are fingerprints of all persons known to have had legal access to the scene. These prints are then compared with the other recovered prints; the ones that do not match may belong to the perpetrator.

processing the scene

- the first step in processing the crime scene is determining who is responsible for what and establishing the composition of the investigative team. The responsibilities should be divided and the performance of activities supervised. - next the investigator in charge must require that all personnel follow procedures to ensure safety and the integrity of the evidence being documented and collected. Security of the evidence and the crime scene must be continually maintained. - the investigator in charge must also be responsible for or supervise the making of photographs, video, sketches, diagrams, measurements, and notes. Photographs, diagrams, and sketches are the primary means by which the crime scene is documented and serve as the official record of the condition and nature of the crime scene. Hand drawn sketches are usually used as a basis from which to develop a computer assisted diagram. Photographs, diagrams, and sketches of the scene are evidence and must be documented and treated as such. Crime scene diagrams should be as detailed as possible and as close to scale as possible. Measurements of crime scenes and the placement of evidence should be included. - with regard to crime scene photographs, each item should be photographed close up and from long range before it is collected. Also the conditions in which the photos were taken (weather, lighting) should be recorded, as should the direction, distance, and view of each photograph. Police departments often use a report form to log photographs. Because the relevance of items at a crime scene may not be immediately known, everything could reasonably be photographed. EX: homicide scenes are often documented with hundreds of photographs. Video is also commonly used to document crime scenes. - various methods can be used when conducting a search for evidence at a crime scene. these methods include the grip, strip, and spiral search patterns. The basic idea for each of these crime scene search methods is to be thorough and systematic and not to overlook or miss any area or any item within the boundaries of the crime scene. In essence, the guiding mindset should be "expect to find evidence". Investigators must be careful that locards exchange principle does not apply to them. EX: when conducting a search, investigators should take precautions to avoid transferring evidence to a crime scene or between crime scenes, and they should avoid excessively handling evidence after recovery. - in the next step in processing the scene, the investigator in charge should determine which items are to be collected and in what order. It is important to remember that any item present in the area may be evidence related to the crime so the rule is "when in doubt, collect" evidence that may be easily altered or destroyed should be collected first. If appropriate and necessary, other methods of evidence collection should be considered and used, including blood pattern documentation, blood illumination techniques, and/or projectile trajectory analysis. - finally, the team members should ensure the proper collection, preservation, packaging, and transportation of evidence, which may depended on the type of evidence at hand. Evidence must be collected and handled properly for it to be of use in an investigation and prosecution. The chain of custody is critical and must be maintained.

the science of DNA

- there are two types of DNA: mitochondrial DNA (mtDNA) and nuclear DNA. MtDNA is found in the mitochondrion in each cell of the body; nuclear DNA is found in the nucleus of a cell. MtDNA is inherited from ones biological mother only. It has limitations compared with nuclear DNA in that it cannot differentiate between individuals who have the same maternal lineage (biological siblings with have the same MtDNA). MtDNA is analyzed when only hair shafts, bone, or teeth are available or when other biological evidence is severely degraded. - nuclear DNA consist of billions of pairs (base pairs) of adenine, cytosine, guanine, and thymine (commonly referred to as A,C,G, and T) structured in the form of a double helix. Very simply, think of the double helix as a twisted ladder and the base pairs as the rungs in the ladder. about 99.9% of the DNA base pairs of each human are the same, but certain areas of the DNA are unique, thus making DNA unique. Of particular importance is that the sequence (or order) of the base pairs repeats and the pattern of repeats are distinct across individuals. Short tandem repeats (STR) are short sequences of DNA (base pairs) that are repeated as a pattern. AS such, DNA typically consist of examining particular STR loci (locations) in the DNA. sometimes reference is made to a thirteen- or twenty-loci DNA profile. In the past the FBI used thirteen specific STR loci to serve as a standard DNA comparison, but as of 2017, twenty loci are now used. the chances that two people will have the same DNA profile (twenty STR loci) can be as remote as one in one billion. The general procedure in conducting DNA analysis is as follows: determine whether the substance is biological evidence and whether it is from a human or animal, isolate the DNA from the biological evidence, analyze the DNA and obtain a DNA profile (pattern) from specific regions (loci) of the DNA, and compare the results of the DNA analysis performed on the biological evidence with a suspect (or sample of possible suspects) to determine if the suspect is the source of the DNA. - the most common method of analyzing nuclear DNA today is known as polymerase chain reaction (PCR). With the PCR technique, the DNA is copied many times (amplified). Two DNA molecules are produced from the original molecule and are repeated many times until millions of copies of the DNA sequence are produced. From these copies a DNA profile can be generated. PCR can still be used if a sample consists of only a few cells or is degraded, but in these cases it is particular susceptible to contamination. - on the basis of DNA testing, one of three conclusions may be drawn. First, the suspect may be included as the possible source of the evidence; however, the certainty of the inclusion will depend on the number of locations on the DNA strand that are examined and how common or rare the resulting DNA print is in the general population. Second, in the same manner than an individual can be included as a suspect, an individual can also be excluded as a suspect. thirds, the results of the analysis may be inconclusive- a person cannot be included or excluded as the source of the evidence. Inconclusive results may occur for a variety of reasons; Ex: the poor quality of the DNA sample may not allow for interpretable results, the evidentiary sample may contain a mixture of DNA from several individuals, or the sample may have been contaminated. - attempts to discredit DNA evidence often involve questioning the procedures used to collect it. All the science and precision of DNA analysis can be foiled if the evidence is collected incorrectly or if claims can be made about the overall integrity of the evidence, as was the case with in the OJ Simpson investigation described in the introduction to this chapter. Even though the scientific basis of DNA analysis has been established, the supreme court has provided for extensive discovery requirements in the admission of the results of the analysis. In Schwartz v. state (1989) the court stated "ideally, a defendant should be provided with the actual DNA sample in order to reproduce the results. AS a practical matter, this may not be possible because forensic samples are often so small that the entire sample is used in test. Consequently, access to the data, methology, and actual results is critical... for an independent expert review." - further, the results of laboratory examinations must be accompanied by in person testimony of the individual who examined the evidence (melendez-diaz v. Massachusetts, 2009); a substitute witness does not satistfy the requirement (bullcoming v. new mexico 2011)

completeing the crime scene investigation

- to complete the crime scene investigation, the investigator in charge should first establish a crime scene debriefing team. This team will discuss and determine the need for any remaining activities prior to releasing the scene and will discuss immediate steps that need to be taken during the follow up investigation. Crime scene findings can be reviewed at this time, and a summary of the evidence collected can be offered. Second, a finally survey of the crime scene should be made to make sure the crime scene investigation is complete and no materials or evidence have been left behind. - finally, the investigator in charge should ensure that all necessary reports and other documentation are completed. this includes reports completed by the initial responding officers, emergency personnel documentation, entry/exit documentation, photographs/videos, crime scene sketches and diagrams, and search warrant or other search documentation. This documentation can serve as a basis to direct further investigative activities and to provide continuity across investigators during the investigation. - an investigator usually only has one shot at a crime scene; therefore, the scene should be treated carefully and processed thoroughly. The value of critical evidence can be quickly destroyed through inappropriate or hasty crime scene procedures.

other types of forensic evidence: ballistics

- various types of evidence are associated with firearms, and various examinations can be done on such evidence. the gun itself can be examined to determine its general condition and whether it is functional. alternations in the functioning of the weapon can be determined, such as if it has been altered to fire in automatic mode. The trigger pull can be tested to determine the amount of pressure necessary to fire the weapon (potentially useful if a perpetrator claims that the gun fired accidentally). fired bullets can be examined to determine their caliber and manufacturer. An examination of shell casings may determine the caliber or gauge and the manufacturer. A suspects DNA or fingerprints may be recovered from firearms and/or shell casings. Bullets that passed through a body may contain the victims DNA and therefore associate the bullet with the victim. - one common and potentially useful form of evidence in crimes involving a fire arm discharge is gunshot residue. Residue patterns may be found on a victim and used to estimate the distance of the muzzle from the victim. In addition, gunshot residue may be found on the hands or clothing of the individual who fired the weapon. Residue tests may be performed on individuals who were at or near a crime scene around the time of a shooting and who are suspected of having fired the weapon. Residue is most likely to be found on the back of the hand in which the gun was fired, but this depends on many factors, including the type of gun. It should be noted that gunshot residue is extremely fragile. - another firearm examination involves test firing a gun to determine whether a recovered bullet was in fact fired from that gun. This comparison is done through the microscopic examination of the markings on the bullet caused by the bullet moving through the barrel of the gun. Although these markings are unique to each weapon, if a recovered bullet is deformed, a valid comparison is difficult to make, if not impossible. factors such as corrosion and/or dirt in the barrel of the gun, the firing of a bullet that is smaller than intended for the gun, and different brands of ammunition can also affect the unique markings on a bullet. The bureau of alcohol, tobacco, firearms, and explosives (ATF) operates the national integrated ballistic information network (NIBIN), which allows for the comparison of recovered bullets and cartridge casing with images of other bullets and casings that have been entered into the system from law enforcement agencies nationwide. by comparing the markings on bullets, crimes (shootings) committed with the same gun can be identified. Research on the impact of the NIBIN, however, has highlighted how analysis delays have reduced the usefulness of the system. - when collecting firearm evidence, it first should be photographed, and if possible, fingerprinted (weapons and unfired cartridges) and examined for DNA. Firearms should be handled with great care and touched as little as possible. A ring device that passes through the trigger guard should be used; this ring prevents contact with the firearm and preserves fingerprints or other evidence on the weapon itself. bullets and casings should be collected and packaged separately in paper envelopes. The number and condition of ammunition (Cartridge, case, shell, or magazine) should be documented. Specially designed boxes should be used for securing firearms. the firearm, bullets, casings, and/or other firearm evidence should not be marked. Clothing submitted for gunshot residue examination should be packaged separately in paper envelopes.

class characteristic vs individual characteristic forensic evidence

- when evidence has class characteristics it can be associated with a group or class of sources. For instance, a paint chip- class characteristic evidence- could be associated with a particular make and model of automobile but not one specific automobile. - when evidence has individual characteristics, it can be identified as originating from one particular source; such is the case when a DNA sample is determined to have come from a particular person. - ERRORS in class characteristics: when evidence with class characteristics is linked to a particular source ( a person), errors in conclusions may result. EX: there are cases where bite marks were erroneously used as individual evidence to obtain convictions that were later determined to be wrongful. Strictly only biological evidence with DNA properties (nuclear DNA) can be accurately considered to be individualistic evidence. With other forms of physical evidence, including bite marks, tool marks, and writing samples, there is not enough science associated with the interpretation and analysis of the evidence. - a related problem with forensics evidence can involve how the results of the tests on the evidence are interpreted and communicated. In particular, forensic examiners and other investigators sometimes use the terms or phrases match ("the hair found in the trunk matched that of the victim"), identical, similar in all respects, or cannot be excluded as the source of. These can be persuasive conclusions, yet there is no consistent agreement as to the scientific meaning of these terms.

preliminary documentation and evaluation of the scene

- with investigators now in charge of the crime scene, it is their responsibility to review the activities of the initial responding officers and to assess (walk through) the scene. safety should be reevaluated, and crime scene boundaries should be confirmed. The crime scene entry log should continue to be used. Investigators should make sure that suspects, witnesses, and victims continue to be separated and monitored, and personnel should be assigned to interview these individuals as soon as is practical. A determination should be made about the necessity of obtaining a search warrant or obtaining consent to search. A path of entry and movement for authorized personnel should be established. The need for additional investigative resources (equipment, legal consultation) should be determined and those resources requested if necessary. Protection of the scene and evidence remains a critical responsibility of all investigators and officers at the crime scene. If multiple crime scenes are present, necessary precautions must be taken to prevent cross contamination of the scenes. - in addition to these activities, it is also important to search for and locate other witnesses who may not have been present at the immediate crime scene and to identify video surveillance that may be relevant to the crime. this is usually performed through a neighborhood canvass. Contact should be attempted at each and every address in the designated area. Whether or not contact is made with residents at each address should be recorded, along with who is (or was) present in the residence. The information provided by the residents should be recorded. A resident may have background information about the place where the crime occurred or the people involved, may have unknowingly seen or heard things that relate to the crime, or may be the one who actually committed the crime. Because of this it is important to collect information about the activities of residents at the time the crime was believed to have occurred. Some residents may not come forward with information unless they are asked by an officer or investigator, so neighborhood canvass can be valuable in developing information. It should be understood by the personnel who conduct the canvass that their role is to collect information, not to give it. Some information about the crime will only be known by the perpetrator and investigators, and the neighborhood canvass should not nullify this fact. In addition to questioning residents, vehicle license plate numbers or vehicle identification numbers of vehicles in the area should be recorded and where those vehicles were parked should be noted. If information arises in the investigation about vehicles that may have been involved in the incident, this information can be useful. When conducting a neighborhood canvass, residents should also be asked about the presence of home surveillance cameras (ring doorbells). Other sources of video surveillance footage should also be explored (businesses, streets)

forensic pathology

An area of forensic science that relates to the study of dead bodies.

touch DNA

DNA analysis of cells discarded simply as the result of touching an object

other types of forensic evidence: toolmarks

a tool mark is any mark created when an instrument (pry bar or screwdriver) has contact with another surface (the wood on a windowsill). the marks left by a tool may indicate the type of tool, the size of the tool, and even the skill of the perpetrator (usually, the fewer the marks/damage, the greater the skill of the perpetrator). though microscopic examination of the marks and a tool, a tool may be linked to a toolmark. Toolmarks are most commonly found around windows and doors in burglary cases. A lack of toolmarks may indicate an alternative method of entry (keys to a door lock or broken window). Toolmarks should be photographed, and casts may be made of the impressions.

secondary transfer

a transfer of DNA between objects or persons via another person or object

physical evidence

also known as forensic evidence or real evidence; evidence that can be seen and held that is created as the direct result of a crime.

other bodily fluids and substances

although relatively uncommon at crime scenes, urine, feces, vomit, and perspiration can all be subjected to DNA analysis and may be valuable evidence in a criminal investigation. As with saliva, it is typically the epithelial tissue cells found in these substances that undergo DNA analysis. The methods used in the recovery and storage of these substances depends on the nature and location of the sample. Samples should be collected with either a sterile eyedropper, cotton swab, or gauze pad and stored in a sterile test tube or other sterile container.

criminalistics

an area of forensic science that relates to the analysis of physical evidence

Biological evidence and DNA: Blood

blood is a common form of evidence found at scenes of violent crimes such as homicides and assaults, and it may also be found at other crime scenes. Blood may be found in a variety of places: on or near the victim; at entrances and especially exits of crime scenes; in or on sinks, wash basins, and towels at the crime scene; on weapons found at the crime scene; on the clothing of victims and perpetrators, and near broken glass. Even if attempts have been made to remove blood, it can often still be located under vinyl flooring, under furniture, and in cracks and crevices. - blood consists of red and white blood cells, which are located in plasma- a nearly clear, watery liquid. An adult body contains about ten pints of blood. In liquid form blood is red, but when dry it can take on several different colors, including brown, black, gray, or even green, depending on the type and color of the surface on which the blood is located. Blood is an excellent source of DNA and as such is often subjected to DNA analysis. The DNA in blood comes from the nuclei of white blood cells as a red blood cell does not have a nucleus. Blood can also be useful for evidentiary purposes through analysis of the pattern and location in which the blood was found. - blood is often very visible to perpetrators and investigators and, as a result, perpetrators maytake precautions to minimize the presence of blood by cleaning the crime scene or cleaning or disposing of articles stained with blood. Such precautions may not be effective, however. Several methods are available to locate blood when it is not visible to the naked eye. An alternative light source of 415 nanometers ("violet" light) may be used to reveal traces of blood not otherwise visible. In addition, the applications of certain chemicals, such as bluestar forensic or luminal, to surfaces that at one time were contaminated with blood can reveal bloodstains via luminescence even if the blood is extremely diluted. The chemical reacts with iron contained in the blood, causing a visible blue glow. Chemicals, however, can destroy the properties of blood, so they are used primarily to detect the presence of blood that might otherwise go undetected. Other blood-illuminating chemicals, such as fluorescein, also react to other substances, such as certain cleaning products, so caution in interpretation is necessary. - depending on the nature and condition of the blood evidence, various methods can be used to collect and package it. Blood in liquid form can be absorbed with a cotton cloth, air dried naturally on a clean piece of paper or drying rack, and then packaged in a paper bag. The paper on which the item dried should be saved and packaged separately. Plastic bags or containers should not be used. The items should not be exposed to extreme heat or direct sunlight. Bloodstained items should be stored in a temperature-controlled environment (60-75 degrees with less than 60% humidity). Blood in liquid form should be refrigerated (but not frozen as tubes of liquid blood may break if frozen) prior to submission to the forensic laboratory. For long term storage, dried blood should be refrigerated or frozen. Blood splatters should be measure and photographed. Each piece of evidence must have a unique reference number. Always take precautions to avoid contamination of the evidence.

class characteristic

features of forensic evidence that allow it to be associated with a group of sources

individual characteristic

features of forensic evidence that allow it to be associated with a particular source

latent prints

fingerprints made when oils and perspiration on fingertips are transferred to a surface and made visible only through the use of various forensic techniques.

Locard's exhange principle

holds that any time an individual comes into contact with a place or another person, something of that individual is left behind and something of that place or other person is taken with the individual

epithelial cells

human tissue cells that cover internal body surfaces and can be used for DNA analysis

The applications of DNA in criminal Investigations: familial DNA searching

instead of a typical CODIS search where recovered DNA is compared against the DNA of known offenders to find an exact match, familial DNA searching (FDS), also referred to as genetic genealogy, involves searching for similar but not exact matches in a genealogy DNA database. In this way the search is focused on identifying a person (a relative) who shares some of the same DNA as the unknown offender. It is not difficult to see the potential benefit of familial searching. If an offenders DNA profile is not contained in the CODIS database, the investigation could be at a dead end. Familial searching, however, does not depend on an exact hit- a near miss is sufficient. If a relative of the offender can be identified through the search, then a family tree may be pieced together using other sources of information to eventually determine the identity of the offender. This technique may also be used to identify a dead body. It is estimated that GEDmatch.com, the website that has been used most often for this purpose, could be used to identify at least 60% of all white Americans through their cousins. however in 2019 GEDmatch instituted a rule that people who submit their DNA to the sit have to opt out in to allow their DNA to be included in law enforcement searches. That policy has reduced the number of profiles the police can search by 90%, from 1.4 million to 140,000. Familial searching received much attention when it was used in 2018 to identify the golden state killer in California, but this tactic has actually been used in hundreds of investigations nationwide. Genetic genealogy has created a need for people who are skilled in creating family trees from DNA - while it is not difficult to see the potential benefits of FDS, it is also not difficult to see the controversy it causes. People who submit their DNA to genealogy services are interested in finding their long lost relatives, not necessarily in having the police use their DNA to find a criminal. The potential also exists for law enforcement authorities to exploit private genetic databases for their own purposes. AS a result, in 2019 the US department of justice issued rules about police use of genetic genealogy. These rules include the following: the ancestry database must inform its users that law enforcement agencies may search the data, to use an ancestry database, the police must identify themselves and their purpose for requesting the search, genetic genealogy should only be used for violent crimes such as murder and rape or to identify human remains, and the police may not secretly take a DNA sample from a suspects relative to help identify the perpetrator. - an emerging issue is at the potential use of CODIS for familial DNA searching. If a suspects DNA did not appear in CODIS, investigators could instead search the data bank for relatives of the suspect and connections could be made using this information. As technology and legal and ethical concerns about genetic genealogy evolve, this tactic may become more commonly and more effectively used to identify offenders.

neighborhood canvass

involves the door to door questioning of residents who live in proximity to the crime scene.

buccal swab

method used to collect DNA from a subject; this involves collecting cells from the inside surfaces of the cheeks

other types of forensic evidence: glass

most often found at hit and run and burglary crime scenes. page 120

cross contamination

occurs when investigators inadvertently transfer evidence from one scene to another

types of fingerprint patterns

page 111

other types of forensic evidence: blood pattern analysis

page 120

other types of forensic evidence: questions documents/handwriting analysis

page 121

other types of forensic evidence: drugs

page 122

characteristics of drugs most commonly encountered on the street

page 122-123

the role of crime labratories in criminal investigations

page 124 forensic science speciality areas pg 124-126

locating DNA evidence

page 93 evidence, possible location of dna evidence, source of dna ex: bite mark-clothing/skin-saliva

Biological evidence and DNA: semen

semen consist of sperm suspended in seminal fluid. One milliliter of semen from a healthy adult male contains approximately 60-100 million sperm cells. Semen also contains epithelial cells (cells that cover internal body surfaces). in liquid form semen is grayish white and has a chlorine type odor. When dry it is clear and starch like. Seminal fluid is most often found as a result of sexual crimes such as rape and can be found with the victim, on the victims clothing, on or in condoms, and in places where the assaults' may have taken place, such as on bed sheets or flooring. DNA analysis can be performed on sperm and/or epithelial cells. - several tests can be performed to identify the presence of semen: the microscopic identification of spermatozoa, the acid phosphatase test (which tests for the presence of the enzyme acid phosphatase found in seminal fluid), choline and p30 (which test for the presence of proteins in seminal fluid), and the use of ultraviolent (UV) light or an alternative light source. Semen and spermatozoa are a rich source of DNA and are often the subject of DNA analysis procedures. However, certain chemicals and UV light can affect DNA structure. - the same procedures for collecting blood apply to the collection of semen. When collecting and packaging suspected liquid semen from crime scenes, it should be absorbed onto a clean cotton cloth or swab, air dried, and then packaged in a clean paper envelope with sealed corners. Semen stained object should be submitted to the laboratory in whole. Suspected semen should be absorbed from immovable objects onto a clean cotton cloth or swab moistened with distilled waters. all semen evidence should be packaged in paper, not plastic. For long term storage, dried semens should be refrigerated or frozen.

forensic odonotologyt

the area of forensic science that relates to the study of dentistry

forensic entomology

the area of forensic science that relates to the study of insects

forensic anthropolgy

the area of forensic science that relates to the study of skeletal remains

DNA (deoxyribonucleic acid)

the genetic building block of all living organisms and unique to an individual, except identical twins

polymerase chain reaction (PCR)

the most commonly used technique of analyzing DNA today

DNA analysis

the process of extracting DNA from cells