Chapter 2

rough sketch

- a sketch, drawn at the crime scene that contains an accurate depiction of the dimensions of the scene and shows location of all objects having a bearing on the case - shows all recovered physical evidence as well as other important features of crime scene - objects are located in the sketch by distance measurements from 2 fixed points (ex. walls off a room); important to be accurate and not just a guess - measurements are made with tape measure - simplest way to designate an item in a sketch is to assign it a # or letter - a legend (list below sketch that correlates the letter to item's description) - should also show a compass heading designating north

estimating time of death

- after a human body expires, it goes through several stages of decomposition - a medical examiner can often estimate time of death by evaluating stage of decomposition in which victim was found

sketches

- after photos have been taken - not required to have skill or time for a polished sketch during early phase of investigation

blood, semen, and saliva

- all suspected (liquid or dried/ animal or human) present in a form that suggests a relation to the offense or people involved in a crime - includes blood or semen dried onto fabrics or other objects, as well as cigarette butts that may contain saliva residues - subjected to serological and biochemical analysis to determine identity and possible origin

potassium level

- another way to estimate time of death is to determine potassium levels in ocular fluid (vitreous humor) - after death, cells within inner surface of the eyeball release potassium levels in ocular fluid - by analyzing K+ present at various intervals after death, rate at which K+ is released into vitreous humor can be determined and can approximate time of death

glass

- any glass particle or fragment that may have been transferred to a person/object involved in a crime - includes windowpanes containing holes made by a bullet or other projectile

physical evidence

- any object that can establish that a crime has been committed or can link a crime and its victim or its perpetrator - its presence must be recognized at the crime scene first - achieves its optimum value in criminal investigations only when its collection is performed with a selectivity governed by the collector's knowledge of the crime laboratory's techniques, capabilities, and limitations

paint

- any paint, liquid or dried, that may have been transferred from surface of one object to another during commission of a crime - ex. transfer of paint from one vehicle to another during collision

integrated ballistic identification system

- comprises of a microscope and a computer unit that can capture an image of a bullet or cartridge

forensic anthropology: skeletal detectives

- concerned primarily with the identification and examination of human skeletal remains - bones are remarkably durable and undergo an extremely slow breakdown process that last decades or even centuries - because of resistance to rapid decomposition, skeletal remains can provide a multitude of individual characteristics - examination of bones may reveal their sex, approximate age, race, and skeletal injury (ex. woman's pelvis is wider) - may also help create facial reconstruction to identify skeletal remains - also helpful in identifying victims of a mass disaster such as a plane crash through bone fragments

offender index

- contains the profiles of nearly 3 million convicted or arrested individuals - law enforcement agencies search this index against DNA profiles recovered from biological evidence found at unsolved scenes - extremely successful in identifying perpetrators because most crimes involving biological evidence are committed by repeat offenders

soil and minerals

- could link person/object to a location - ex. soil embedded in shoes and insulation found on garments

forensic index

- currently contains about 110,000 profiles from unsolved crime-scene evidence (based on a match, police in multiple jurisdiction can identify serial crimes, allowing coordination of investigations and sharing of leads developed independently

search for burglary

- efforts will be made to locate tool marks at point of entry * in most crimes, a thorough and systematic search for latent fingerprints is required

forensic entomology

- study of insects and their relation to a criminal investigation - commonly used to estimate time of death when circumstances surrounding crime are unknown - after decomposition begins, insects such as blowflies are the first to infest the body (eggs are laid in human remains and ultimately hatch into maggots or fly larvae -> consume human organs and tissues) - can identify specific insects present in body and approx how long a body has been left exposed by examining stage of development of fly larvae - time required for stage development is affected by environmental influences such as geographical location, climate, and weather conditions - ex. cold temp. hinder development of fly eggs into adult flies

forensic databases

- ultimate contribution a criminalist can make is to link a suspect to a crime through comparative analysis - linking the evidence to a suspect is important - crime lab is now on forefront of investigation seeking to identify perpetrators

substrate controls

- uncontaminated surface material close to an area where physical evidence has been deposited; used to ensure that the surface on which a sample has been deposited does not interfere with lab tests - ex. normally collected at arson scenes

fingerprints

all prints of this nature, hidden (latent) and visible ammunition, suspected of being involved in a criminal offense

hair

animal/human

explosives

any device containing an explosive charge, as well as objects removed from scene of an explosion that are suspected to contain that residues of an explosive

wood and other vegetative matter

any fragments of wood,sawdust, shavings, or vegetative matter discovered on clothing, shoes, or tools that could link a person/object to crime location

documents

any handwriting/typewriting submitted that authenticity or source can be determined - related items include paper, ink, indented writings, obliteration, and burned or charred docs

fibers

any natural or synthetic fiber whose transfer may be useful in establishing a relationship between objects and/or people

drugs

any substance seized in violation of laws regulating sale, manufactured, distribution, and use of drugs

food in stomach

can also help estimate when a person's last meal was eaten

considerations in searching crime scene

depends on locale and size of area as well as actions of suspects and victims - when possible, 1 person should supervise and coordinate collection of evidence - without proper control, search may be conducted in confusion with needless duplications - collectors may subdivide the scene into segments or search may start at some outer point and gradually move toward center of scene in circular fashion - areas searched must include all probable points of entry and exit used by the criminals

vehicle lights

determines whether it was on or of at time of impact

plastic bags

disposable polyethylene bag such as garbage bag may be evidential in a homicide or drug case

petroleum products

ex. gasoline residues removed from scene of an arson, or grease and oil stains that may suggest involvement in crime

securing and recording the crime scene

failure to protect a crime scene properly or record its details accurately may result in the destruction or altering of evidence, or hinder the search or perpetrator by misleading investigators about the facts

probability

frequency of occurrence of an event

serial #'s

includes all stolen property submitted to lab for restoration of erased identification numbers

plastic, rubber, and other polymers

may be linked to objects recovered in possession of criminal suspect

dealing with physical evidence

once found, physical evidence must be collected and stored in a way that preserves its integrity for forensic comparison and analysis

standard/reference sample

physical evidence whose origin is known, such as blood or hair from a suspect, that can be compared to crime-scene evidence

impressions

tire markings, shoe prints, depressions in soft soils, and all other forms of tracks - glove and other impressions, bite marks in stain/foodstuffs

examination of physical evidence

usually examined by a forensic scientist for identification/comparison

mobile crime laboratories

vehicles that carry the necessary supplies to protect crime scene; photograph, collect, and package physcial evidence; develop latent prints - not designed to carry out func. of chem lab

FBI's Combined DNA Index System (CODIS)

- CODIS enables federal, state, and local crime labs to electronically exchange and compare DNA profiles, thereby linking crimes to each other and to convicted offenders - all 50 states have enacted legislation to establish a data bank containing DNA profiles of individuals convicted of felony sexual offenses - contains forensic index and offender index

after securing the scene

- a lead investigator then starts evaluating - determines boundaries of scene, and then establishes perpetrator's path of entry and exit - items must be documented and photographed - investigator then proceeds with initial walk-through of scene to gain overview and develop strategy for systematically examining and documenting entire crime scene

chain of custody

- a list of all people who came into possession of an item of evidence - failure to have everyone accounted for may lead to serious questions regarding the authenticity and integrity of evidence and the examinations for it - recording location of evidence, marking it for identification, and properly completing evidence submission forms for lab analysis guarantee integrity - all items should be carefully packaged and marked upon retrieved - normally collector's initials and date of collection are inscribed directly on the article - everyone involved in collection and transportation of evidence may be requested to testify - chain of custody should be kept to a minimum

rigor mortis

- a medical condition that occurs after death and results in stiffening f muscle mass; rigidity of body begins within 24 hrs of death and disappears within 36 hrs of death

integrated automated fingerprint identification system

- a national fingerprint and criminal hsitory system maintained by the FBI (1999) - contains fingerprints and corresponding criminal history information for nearly 50 million subjects (or 500 million fingerprint images), which are voluntarily submitted to FBI by state, local, and federal law enforcement agencies - a crime-scene fingerprint or latent fingerprint is a dramatic find for the criminal investigator 1. once quality of print has been deemed suitable for the IAFIS search, latent-print examiner creates a digital image of print with either a digital camera or a scanner 2. next, examiner (with aid of a coder) marks points on print to guide the computerized search 3. print is then electronically submitted to IAFIS and within minutes, search is completed against all fingerprint images in IAFIS - examiner may receive a list of potential candidates and their corresponding fingerprints for comparison and verification

algor mortis

- a process that occurs after death in which the body temp. continually cools until it reaches the ambient or room temp. - rate of heat loss is influenced by location and size of body, victim's clothing, and weather conditions - can only estimate approx. time period since death - general rule: beginning about an hour after death, body loses heat at a rate of approx. 1- 1.5 degrees Fahrenheit per hours= until body reaches environmental temp.

secure and isolate the crime scene

- first officer at crime scene must preserve and protect area as much as possible - first priority should be given to obtaining medical assistance for individuals in need and arresting perpetrator - ASAP, extensive efforts must be made to exclude all unauthorized personnel from scene - as more officers arrive, measures are taken to isolate area - ropes or barricades along with strategic positioning of guards prevent unauthorized access - violent crimes are susceptible from higher level police officials and members of press, as well as emotionally charged neighbors and curiosity seekers - every person at the scene has potential to destroy physical evidence (even if by unintentional carelessness) - to have proper control over scene, the officer protecting it must have authority to exclude everyone, including fellow police officers not directly involved *securing and isolating are critical

tools for evidence collection

- forceps and similar tools may be used to pick up items - unbreakable plastic pill bottles with pressure ids are great for hairs, glass, fibers, and other trace evidence -alternatively, manila envelopes, screw cap glass vials or cardboard pill boxes are sufficient - ordinary mailing envelopes should not be used as evidence containers because powders and fine particles will leak out of their corners - small amounts of trace evidence can be packaged in a carefully folded paper (druggist fold) - consists of folding one end of paper over 1/3, then folding the other end (1/3) over that, repeating the same process from the other 2 sides - outside edges are tucked into each other to produce a closed container - if bloodstained materials are stored in airtight containers, accumulation of moisture may have mold - wrapping paper, manila envelopes or paper bags are recommended - all items of clothing must be air dried and placed individually in separate paper bags to ensure constant circulation of air through them - prevents growth of mold and mildew - charred debris recovered from suspicious fire must be sealed in an airtight container to prevent evaporation of volatile petroleum residues - paint cans or tightly sealed jars are recommended

product rule

- formula to determine how frequently a certain combination of characteristics occurs in a population - states that one must first determine probability of each characteristic occurring separately, then multiply together frequencies of all independently occurring characteristics

livor mortis

- heart stops pumping, blood begins to settle in parts of body closest to the ground - skin appears dark blue or purple in these areas - skin does not appear discolored in areas where body is restricted by either clothing or an object pressing against body (can be useful in determining if position was changed after death)

manner in which death occurred is classified into 5 categories:

- homocide - suicide - accident - undetermined * based on circumstances surrounding the incident

tool marks

- includes any object suspected of containing impression of another object that served as a tool in a crime - ex. screwdriver/crowbar -> impressed into/scraped along wall

use of videotape

- increasingly popular due to decrease in cost - same principles as photos apply - long shots as well as close-ups should be taken in a slow and systematic manner - desirable to have a crime-scene investigator narrate events and scenes being taped while another records - cannot be used in place of still photos because of the definition it provides to the human eye

the murder scene: death and autopsies

- intense physical analysis is done primarily by a forensic pathologist, often aided by skills of specialists including forensic anthropologists and forensic entomologists - forensic pathology involved study of medicine as it relates to application of the law, particularly criminal law - most often involves investigation of sudden, natural, unexplained or violent deaths

record the scene

- limited time to work a crime site in its untouched state - useful during later investigation - required for presentation at a trial in order to document condition of crime site and to delineate location of physical evidence - photograph, sketches, and notes are the 3 methods of crime scene recording - ideally all 3 are used but personnel and monetary limitations often prohibit the use of photography at every crime site - under these circumstances, guidelines will establish priorities for deploying photographic resources

national integrated ballistics information network

- maintained by the Bureau of Alcohol, Tobacco, Firearms, and Explosives, allows firearms analysts to acquire, digitize, and compare markings made byh a firearm on bullets and cartridge casings recovered from crime scenes - currently has 236 sites that are electronically joined to 16 multistate regions

autopsy

- medical dissection and examination of a body in order to determine cause of death - medical examiners must perform autopsies if a death deemed suspicious or unexplained - ex. a decedent with a gunshot wound and a gun in his hand may appear to have committed suicide, but autopsy may reveal that victim actually died of suffocation and gunshot wound occurred after death to cover up circumstances surrounding commission of a crime

collect physical evidence

- minute traces of blood may be discovered on garments only after a thorough search - presence of hairs and fibers may be revealed in vacuum sweepings or on garments only after close lab scrutiny - important to collect possible carriers of trace evidence - may be necessary to take custody of all clothing worn by participants in crime - critical areas should be vacuumed and sweepings submitted to lab for analysis - portable vacuum cleaner equipped with a special filter attachment is suitable - fingernail scrapings may contain minute fragments of evidence capable of linking assailant and victim - undersurface of each nail is best scraped with dull object like a toothpick to avoid cutting skin - scrapings must be subjected to microscopic examination - search must extend beyond crime scene to autopsy room - victim is carefully examined to establish a cause and manner of death tissues and organs are retained for pathological and toxicological examination - arrangements must be made between examiner and investigator to secure a variety of items that may be obtained from body

computer-aided drafting (CAD)

- standard method for reconstructing crime scenes from rough sketches - software, ranging from simple, low-cost programs to complex, expensive ones contains pre-drawn intersections, roadways, buildings, and rooms for info to be entered - library provides a variety of images that can be used to add intricate details such as blood spatters/crime-scene sketch equipped with a zoom func.: can focus on a specific area for a more detailed pic - allow user to select scale size suitable for courtroom

photography

- most important thing is it has to be unaltered - unless injured people are involved, objects must not be moved until photographed from all necessary angles - if objects are removed, positions changed, or items added, photos may not be admissible as evidence at trial and intended value will be lost - if evidence has been removed or moved prior to photography, fact should be noted in report, but evidence should not be reintroduced into scene in order to take photos - each crime scene should be photographed as much as possible - should include area where rime actually took place and all adjacent areas where important acts occurred before or after - overviews photos of entire scene and surrounding area, including points of exit and entry, must be taken from various angles - if crime took place indoors, entire room should be photographed to show each wall area - rooms adjacent to actual crime site must be similarly photographed - if it includes a body, photos must be taken to show its position and location relative to entire scene - close-ups depicting injuries and weapons lying near body are also necessary - after body is removed from scene, surface beneath body should be photographed - when size of an item is significant, a ruler or other measuring scale may be inserted near object and included in photo as point of reference - digital revolution = enhanced photographic capabilities to crime scene - ex. individual photos can be stitched together electronically to reveal a near 3-d panoramic view - with aid of computer, any area of scene captured digitally can be enhanced and examined in fine detail

role of forensic pathologist

- must answer basic questions: who is the victim? what injuries are present? When did the injuries occur? Why and how were the injuries produced? - primary role of the medical examiner is to determine cause of death

notes

- must be constant throughout processing of crime scene - must include a detailed written description of scene with location of items of physical evidence recovered - must also identify time item of physical evidence was discovered, by whom, how and by whom it was packaged and marked and the disposition of item after it was collected - written record may be only source of information for refreshing one's memory months, perhaps years, after a crime has been processed - mjust be sufficiently detailed to anticipate this need - detailed notes can be taped faster than written - another method of recording notes is to narrate a videotape of crime scene (must be then transcribed into written doc)

procedures for collecting and packaging physical evidence

- must be handled in a way that prevents any changes - changes can arise throughn contamination, breakage, evaporation, accidental scratching or bending, or loss through improper or careless packaging - integrity of evidence is best maintained when it's kept in its original condition as found at crime site - whenever possible, should be submitted to lab intact - blood, hairs, fibers, soil particles, and other types of trace evidence should not normally be removed from garments, weapons, or other particles that bear them - entire object should be sent to labs for processing - if evidence is adhering to an object in a precarious manner, good judgment dictates removing and packaging the item - if found adhering to large structure (wall, decor, floor), remove specimen with forceps - in case of bloodstain, one may either scrape stain off surface, transfer stain onto a modified swab, or cut out area of object bearing stain

conduct a systematic search for evidence

- must be thorough and systematic - investigator must not overlook any pertinent evidence for a factual, unbiased reconstruction of the crime - failure in a thorough search can lead to accusations of negligence or charges that the investigative agency knowingly "covered up" - some police agencies have trained field evidence techs to search crime scene - have equip and skills to photograph the scene and examine it for the presence of fingerprints, footprints, tool marks, or any other type of evidence that may be relevant

finished sketch

- precise rendering o crime scene, usually drawn to scale - constructed with care and concern for aesthetic appearance - must reflect info contained within rough sketch in order to be admissible in court

comparison

- process of ascertaining whether 2 or more objects have a common origin - 2 step procedure: 1. combinations of select properties are chosen from suspect and standard/reference specimen for comparison - which and how many depends on type of materials being examined 2. must draw conclusion about origins of specimens - if 1 or more properties don't match up -> not the same/same source - same properties don't necessarily mean same source

indentification

- process of determining a substance's physical or chemical identity with as near absolute certainty as existing analytical techniques will permit - ex. asked to identify chemical composition of preparations that may contain illicit drugs such as heroin, cocaine, or barbiturates - may be asked to identify gasoline residues recovered from debris of a fire, or nature of explosive residues (ex. dynamite/TNJ) - identification of blood, semen, hair, or wood would, or species origin (ex. did bloodstain originate from human or dog/cat?) 1. process first requires adoption of testing procedures that give characteristic results for specific standard materials - once tests have been established, they may be permanently recorded and used repeatedly to prove identity of suspect materials - ex. to ascertain suspect powder is heroin, test results must be identical to those previously obtained from known heroin sample 2. I.D. requires that # and type of tests needed to identify a substance be sufficient to exclude all other substances

class characteristics

- properties of evidence that can be associated only with a group and never with a single source - ex. chance of 2 single-layer car paint chips of a similar color originating from same car is not as likely as comparing 2 paint chips with 7 similar layers

individual characteristics

- properties of evidence that can be attributed to a common source with an extremely high degree of certainty - ex. matching ridge characteristics of 2 fingerprints, comparison of striations on bullets or tool marks, comparison of irregular and random wear patterns in tire or footwear impressions, comparisons of handwriting characteristics, fitting together of irregular broken objects' edges, matching plastic bags - conclusion must be sustained by practical experience - ex. French scientist Victor Balthazard determined probability of 2 individuals having same fingerprints is 1 out of 1 x 10^60

powder residues

- results from discharge of firearm

search for homicide

- search will center on the weapon and any type of evidence left as a result of contact between victim and assailant - cross-transfer of evidence (hairs, fibers, and blood) is useful in linking suspects to crime site and for telling events that happened during crime

submit evidence to laboratory

- usually submitted by personal delivery or mail shipment - determined by the distance the submitting agency must travel to laboratory and urgency of case - if delivered personally, deliverer should be familiar with case to facilitate any discussions between laboratory personnel and the deliverer concerning specific aspects of case - postal regulations restrict shipment of certain chemical, and live ammunition and prohibit mailing of explosives - lab must be exercised in packaging of evidence in order to prevent breakage or other accidental destruction - most labs require that evidence submission form accompany all evidence submitted - brief description of the case history will allow the examiner to analyze the specimens in a logical sequence and make proper comparisons - will also facilitate the search for trace quantities of evidence - analyst won't be bound to adhere strictly to specific tests requested by investigator - during examination, new evidence may be uncovered (complexity may change) - a list of items submitted for examination must be included on evidence submission form - each item is packaged separately and assigned a # or letter listed in an orderly and logical sequence on form

assessing the value of evidence

- value lies in its ability to corroborate events with data in a manner that is as free of human error and bias as possible - Wayne Williams was charged with the murders of 2 individuals in Atlanta, Georgia, and linked to murders of 10 boys - essential element to case involved associating him with victims through fiber evidence (28 diff. types of fibers linked)

search for hit-and-run

- vehicle searches must be carefully planned and systematically carried out - nature of case determines how detailed search must be - outside and undercarriage of car must be examined with care - particular attention is paid to looking for evidence of cross-transfer - traces of broken glass or paint may be located on victim - in cases of homicide, burglary, kidnapping, etc. all areas of vehicle are searched

items to be collected and sent to forensics lab:

- victim's clothing - fingernail scrapings - head and pubic hairs - blood (for DNA typing) - vaginal, anal, and oral swabs (for sex-related crimes) - recovered bullets from body - handswabs from shooting victims (for gunshot residue analysis) * lengthy delay in obtaining these items will diminish or destroy their forensic value

cautions and limitation in dealing with physical evidence

- weight/significance is determined solely on the trier (jury) - physical evidence can also serve to exonerate no 2 things in the world are alike in every detail - distinguishing evidential variations from natural variations is not always easy - learning how to use microscope is one thing; interpreting observations and data proficiently is another

buccal swab

a swab of inner portion of the cheek, performed to collect cells for use in determining the DNA profile of an individual