Module 4: Forensic Analyst

Laboratory and Forensic Examinations of Firearm Evidence

- A broad array of services are offered by the crime lab concerning the examination of firearm evidence. - From a foundational standpoint they are the authority who establishes the firearm functions, serving as verification of that fact including details about how it does so. - Beyond that the identification of projectiles, shell cases, and firearms to one another is the summary of their mission. - Thanks to NIBIN this process is aided in the same manner AFIS and CODIS help identify fingerprints and DNA. - Consider if you will the value in being thorough in your search through followup investigations. - It seems natural for criminals to dispose of the firearm used in an offense. - They are often never found. - Shell casings from a scene however often may feature individual characteristics which may prove invaluable when a follow-up search warrant at the suspect's residence yields a spent shell case he held on to for whatever reason and it was fired from the same weapon. - The lab report establishing this fact is nearly as impactful as having the weapon itself. - This point builds upon the closing remarks from the fingerprint section about diligence and thoroughness.

Chemical Examinations

- Again employing a two-step process, chemical examinations begin with wet procedures in order to screen or in some cases prepare a sample for further analysis. - The confirmatory step then is accomplished through instrumental procedures as detailed further in the text.

Analysis of Plant Material

- As mentioned in the text, the majority of plant matter analysis focuses on confirming a substance is marijuana. - Though this may of course change in the future. The learning point here is the addition of the physical observation methods used. - To confirm plant material a physical observation is made looking first for class characteristics then species specific individual characteristics. - Beyond this traditional chemical examinations are performed as described in the text.

Y-Chromosome STR

- As technology develops we can glean more information from less material, specifically referring to DNA. - Beyond that even, the DNA material contributed by a male can be distinguished from a mixture, with obvious useful implications in the criminal justice field which are spelled out in the text.

Tool Marks

- As we move into the last section of chapter 14 we see tool mark analysis is not as straight forward as some of firearms analysis is due to the variability of which a mark can be made. - Firearms function repetitiously in a certain and predictable manner within a framework. - The infinitely variable manner in which a person can apply force with a tool poses challenges to the examiner in reproducing sufficient standards for comparison. - You may find through reading this section that more items than you might have originally realized can be valuable for tool mark analysis. - As we will see in Chapter 15, a significant hurdle in this discipline is having a standard to compare to. It is hoped through either diligent crime scene processing or investigative progress a tool will be located which is believed to have been used, to be confirmed by laboratory analysis.

Mitochondrial DNA

- As you read through this section of the text you are informed of a potential forensic advantage to extranuclear DNA by virtue of its larger quantity per cell as opposed to nuclear material. - As you consider this can you think of another great use for mitochondrial DNA then on a larger and more devastating scale? - When investigating a mass casualty event, whether it is a terrorist attack or simply a commercial plane crash, The importance of identification is paramount. - Traditional DNA methods may fail due to degradation where mitochondrial DNA may survive. - With heavy damage and fragmented remains many if not all traditional methods of identification may be nullified. - A severed hand or even just a finger may be useful in obtaining a post-mortem fingerprint however if there are no antemortem standards of comparison available it is worthless. - Consider however that everyone has a mother and father. - The advantage here is the opportunity to find a DNA reference standard available in surviving relatives. - Take note from the information in the text however if a mother and daughter, or two sisters, were both killed and fragmented in the plane crash, their mitochondrial DNA is indistinguishable from one another.

Fingerprint Classification

- Building on the previous section devoted to the history of fingerprints it is important to have an awareness of the Henry system of classification which was quite advanced in its time and is still today. - This provided a means to manage a large volume of information in the form of fingerprint standard cards, and some means of search ability however not to the extent that would be necessary to take full advantage of a single fingerprint lifted from a crime scene.

Fingerprint Patterns

- Building upon the previous jury-interface point, a competent expert witness can connect with the jury by explaining the arch, loop, and whorl. - Many people will almost automatically look at their own fingerprints with the new knowledge in an effort to determine their own patterns. - In doing so we have brought the juror into the event, made it interesting to them, and helped them to invest in the evidence. - An explanation of the pattern is well covered in our text including the subcategories of each, with necessary illustrations.

Dye stains

- Concerning previously CA fumed items (described above), the ability to further increase the sensitivity of the process through application of a dye stain gives agencies even greater reach for solving cases through physical evidence. - Consider a drug investigation in which a plastic bag is recovered containing some kind of illegal substance. - While an initial fuming may result in little to no visible ridge detail, the application of a dyestain sensitive to a forensic light source may mean the difference between a fingerprint of value for comparison and not.

DNA Entering the Courts

- DNA is maybe the most powerful and expected form of evidence there currently is. - While simplistically stated it may be just another form of biometric identification, like fingerprints though measured on a much smaller scale, the route to the identification is much different. - Further, the incredible forensic usefulness lies in its diversity. It comes from so many sources, as we talked about in Chapter 8. DNA is young, but advanced and credible, and well accepted in a forensic setting. - In fact it is expected. We are now celebrating thirty years since Colin Pitchfork was caught thanks to DNA evidence.

Drug and poison classes

- Drugs of no known medicinal value, natural substances of controversial opinion on worth, as well as FDA approved prescription medications are within the area of concern for the toxicologist. - As the text refers to, opiates are a large class of drugs which are both prescribed medicinal, though abused, as well as illicit substances manufactured and delivered illegally.

Manufacture of Firearms

- Earlier in the course we discussed class characteristics compared to individual characteristics when we used the Nissan Rogue as an example. - Nissan is the class characteristic and Rogue is the individual. - In the same manner, a manufacturer of a firearm, such as Remington, Winchester, or Glock makes design choices which may be unique to their weapons. - Unlike auto manufacturers however some of the characteristics as described in the text such as style of rifling of a barrel may be shared by more than one manufacturer.

Iodine fuming

- Effective at developing fingerprints non-destructively and on irregular surfaces though a very inefficient searching technique due to a highly focused area of fuming coupled with how fast the visibility fades

Drugs in the Body

- In order to be effective the toxicologist must be guided by ADME, Absorption —> Distribution —> Metabolism —> Excretion. - They must keep this in mind as they consider not only where to look in the body but in caring for what they find as well as interpreting the results against a timeline of bodily functions.

History of Fingerprints

- In that, the exploration of fingerprints has lasted thousands of years, far in excess of any other means of forensic identification certainly, there is a substantial amount of information dotted along its timeline. - Though the original and oldest source of awareness may be in conflict like many things, it's important to note a few of the influential persons who have moved the technology along to what it is today. - The case study from Argentina for example of the murder of the Rojas children in 1892 is very significant in that it demonstrates a forensic application of crime scene and analyst principles which are still applied today.

Analytical Methods and Standards of Analysis

- It is in this area where the work gains its credibility and ultimately its defensibility. - By adhering to best practices and/or standards adopted in the industry members of the forensic analysis community beyond just the toxicology and seized drug analysis we're talking about here are able to defend their findings in court and demonstrate credibility to a jury who ultimately are not educated in the field.

Non-medicinal agents

- The toxicologist stays aware of many substances which are introduced into our bodies both intentionally and not. - The recreational application of alcohol is a large portion of this work. - Additionally, carbon monoxide deaths are quite common both intentionally through suicide as well as accidental because of either defect or negligence. - In situations of natural disasters many families use portable generators to power portions of their home. - Often the generator is placed in such a way that lacks adequate ventilation. - Whether it is out of negligence or an attempt to avoid theft many whole families have died this way. - A common method of suicide is to contain the exhaust gases from a car within an enclosed space such as a garage or direct the fumes into an enclosed space such as by affixing tubing to the exhaust pipe in order to channel the fumes into the passenger compartment.

Fingerprint Identification: The Heart of the Matter

- It is in this area where we appreciate the culmination of many people's efforts. - In my effort to positively impact that system let me illustrate less thought-of variables in that system which can have a significant impact. - It is certainly important to have a fingerprint analyst who is well trained and on their A-game. - They must be focused and dedicated to the craft and their reputation. - However the last person in a string of individuals who play a role in the identification. - If the crime scene investigator did a poor job of searching for the prints they'll have missed some. - If they use too much powder they'll obscure the print. If they were otherwise careless they may have only lifted part of the print, - If the person working in a jail in another state in another decade did a poor job of collecting an arrested person's print standards however, all of the work done in the current decade may be for nought. - If the jailer on the other hand took the time to do a good job by making a second effort at obtaining ridge detail in the hard to reach portions of the hand, being thorough in their job, they may have made the difference between identifying a rapist who happened to have only been arrested once years and years ago when he was in college for a disorderly intoxication charge. - Those quality prints obtained by someone who took the time to do their one job well made a difference. - The crime scene investigator who took the time to not only collect a discarded flashlight at the scene but also took its batteries out and fingerprinted them made a difference. - The fingerprint analyst who took the time to replot several different points on the print and search it again, made a difference.

Tire Impression Evidence

- Most obviously the size of the impression can be substantially larger. - It isn't practical to collect a plaster cast of more than around 36" linear distance at most and that itself is cumbersome. - The impression, if a substantial length of it is truly of good quality, must be sectioned in such a manner to make it workable. - The sectioning can almost be done arbitrarily with the field personnel's fingers crossed for good luck as they'll have no way of knowing if they're cutting through a portion that contains individual characteristics or not. This is almost never going to be plainly visible to the naked eye. Despite this, an effort should be made to section the impression perhaps where there is already a clump of grass interfering, or a root, etc... - By overlapping the photography sections the loss of evidence can be minimized as stated in the text. - Imagine you have a burglary of a used car lot in which the for sale cars are parked on a dirt lot. - The office was broken into, the car keys taken, and cars missing from the lot. - You can see a set of footwear impressions walking up to the left side of a car near where the driver's door would be, then they disappear. - Further you know it is the driver's door because you can see the set of wheels which pivoted in place prior to moving, and you can also see one of the footwear impressions also pivots on top of itself then disappears, as someone turns to sit in a car then lifts their feet into it. -Do you have the awareness to realize the impression evidence of the tires hold no probative value for your case and your sole focus should be on the footwear impressions. - If so you are maintaining an awareness for the concept of reconstruction.

Types of Evidentiary Fingerprints

- Recognition of the type of fingerprint is highly important in order to know how to proceed with its development and/or preservation. - Additionally, maintaining an awareness of the substrate the fingerprint is deposited on is important in order to be cautious of the type of process you apply as it may work very well on the fingerprint but be destructive to the substrate. - For example, if you are attempting to develop a bloody fingerprint on a painted wall you may be faced with a choice of using amido black in a water-based carrier or a methanol one. - The staining power may be greater with the methanol product however it may also blister and peel the paint, destroying the print in the process. - This is the kind if irreparable damage which can be done to physical evidence without keeping a broad perspective on the actions being taken at a scene. If the bloody print is on glass, tile, or some hardened material which is impervious to methanol, the greater reward may be achieved. - Another important aspect of preservation of fingerprints comes in knowing if it is a patent or plastic print. It may be that any process applied to a patent print will result in a poorer final product when all that is necessary is photography of the print using oblique lighting, or lighting applied at a very shallow angle to the surface the print is deposited on. - For this reason there is a common flow chart guiding the sequential process of fingerprint processing beginning with non-destructive methods such as observation, lighting, and photography prior to applying a physical or chemical process which could destroy the print.

Short Tandem Repeats

- STR is still the current analysis standard in the industry. By appreciating the relationship of adenine (A), thymine (T), cytosine (C), and guanine (G) we are able to begin to understand the power of the STR analysis. - Review Figure 9.6 in the text as you take note of the consistent pairing between A and T, and C and G. This fundamental principle helps to understand the process of replication, as the identified sequence is able to be predicated and copied repetitiously. - By choosing 15 loci from which to measure the STR, analysts are able to provide staggering results to defend their identification through statistical analysis.

Saliva

- Saliva itself isn't of greatest interest in the forensic setting, rather the great quantity of skin cells it generally contains as your mouth constantly renews itself. - As with our previous section on seminal fluid, the specificity of the material may prove useful in cases such as sexual violence where the style of DNA deposition itself may prove or disprove a crime. - It's important to note from the text when discriminating for saliva specifically one cannot test for saliva itself rather a digestive enzyme which is found at much higher levels in saliva than other body fluids.

Computer-Based Fingerprint Files

- The advent of computer databases and algorithmic search techniques brought about a significant shift in the value of fingerprint evidence obtained through investigation. - Take note as described in the text that the central repository of fingerprint records is housed nationally in the United States by the FBI.

Analytical Methods in Forensic Toxicology

- The application of complex confirmatory tests is applied through triage. - As noted in the text, the bi-layered approach to testing is done to establish credibility, by not only using two methods of detection but also finding the substance in two different sources within the body. - Triage comes in by using a broad-sweeping test which may not be specific but is simpler, in order to guide the more complex confirmatory test. - In doing so the efforts are saved at confirming a substance you already have no reason to believe is there. - The equipment used in the toxicological analysis is far from what a layman can have a deep understanding of without focused intentional study. - These analytical methods are perhaps the area of our study that take the greatest step away from training and experience-based application of common sense and critical thinking skills. - Nevertheless, a basic understanding is important for a well-rounded education in our topic.

CODIS

- The database maintained by the Federal Bureau of Investigation which houses the DNA profiles of designated individuals including felons as well as missing or unidentified persons. It stands for Combined DNA Index System.

Instrumental Examinations and IR Spectroscopy

- The gas chromatography-mass spectrometry platform is widely used though other methods may be well suited for analysis as described here. - Specifically the use of infrared spectroscopy applies to seized drug analysis because of its applicability to solid samples which are often seen. - The specific process is further detailed in this section of our textbook.

Forensic Footwear Evidence

- The individual characteristics used for identification come in the form of wear patterns combined with specific damage and/or artifacts observed within the tread. - The normal wear and tear of use is what produces the individual characteristics. - Unfortunately, they can be ever-changing with continued use. - Some reconstructive value can be obtained from careful examination of the impression evidence. - If you're fortunate enough to have a clear set of footwear impressions leading into the scene and another leading out look closely and see if the ones leading in are uniformly flat and even. - If so, are the ones leading away from the scene different? Is the toe dug in a bit as the subject left in more of a hurry than they arrived? -Can you find an impression on top of another such that you can definitely say the one leading a certain direction occurred before or after the other? - Much of the discussion for footwear evidence is duplicated in tire impression evidence. Consider that in the next section. - Specifically in the documentation and preservation of the impressions this is true. - While traditional crime scene photography is required in order to place the impressions in the scene and provide accountability, the specifics of examination-quality photographs described in the text are required and some of the factors will be emphasized here. - The camera mounted directly above the impression on a tripod reduces any distortion caused by aligning the camera at any angle other than perpendicular to the focal plane - The use of a tripod also allows the photographer to maximize the depth of field by selecting a higher F stop, or smaller aperture size, thus producing a greater quality image

Scope of Seized Drug Analysis

- The mission of the seized drug analyst is focused, serving a specific function within codified regulations. - The decisions made are centered around quality control and accountability of evidence. - Quantification may be necessary depending on the specifics of what crime is being investigated.

Drugs and the Controlled Substances Act

- The need for seized drug analysis is embedded in the purpose of the CSA, providing the forensic support necessary to enforce its regulations. - The CSA delineates drugs into differing schedules depending on their known medicinal value or likelihood for abuse.

Seminal Fluid

- The second most frequently used body fluid within investigations, seminal fluid is useful also for DNA analysis but in the form of the epithelial cells it contains as well as the sperm it carries. - While we want to eventually reach the position of a solid DNA profile matched to an individual through overwhelming statistical comparison in the quintillions, this may not be enough. - If an analyst testifies that Person A's DNA profile was found on the skin of Person B, where Person A is the brother of Person B, this fact alone may not be very useful in proving anything as siblings often come in contact with one another through normal life. - If however, the testimony is that the DNA profile of Person A was obtained from sperm cells which were found on Person B, this may be much harder to explain. - This fact also aids in the bigger picture in that it provides more specific information concerning the reconstruction of events.

Ninhydrin

- The standard for porous item processing such as paper and raw wood. - The application is easy and almost foolproof as long as great ventilation such as a high volume ducted vent hood is used. Exposure to its fumes pose a significant health risk. - The efficacy of print development is consistent and relied upon. - The final product is durable and fixed for sufficient time necessary to analyze the print.

Applications of Forensic Toxicology

- The toxicologist is the lab professional who often works in concert with the medical examiner's office conducting post-mortem analysis of blood, urine, or the vitreous humor. Refer to Table 10.1 in the text for a comparison of these and other sources of samples from the body. - By performing this analysis with expertise they can aid in determining the manner of death, whether ingestion of a substance which caused death was done so accidentally or intentionally based on levels of concentration. - Workplace drug testing is useful in pre-employment screenings as well as for cause. - Either of these sub-disciplines within toxicology require a search function, or a wide net, in order to be successful. - This lies in contrast to the seized drug analyst we'll discuss later

Collection of Firearms-Related Evidence

- There may and likely will be useful reconstructive value in documenting the specifics of how a firearm is found when related to a crime. - Finding a semi-automatic handgun with a loaded magazine inserted and seated, with the action closed or "in battery" but no cartridge in the chamber at the scene of a reported suicide via gunshot wound may be troubling for example. - Finding a revolver with the hammer down on top of a live chamber at the suicide may also pose great questions as to the sanctity of the scene. - Unfortunately, large quantities of first responders are not actively thinking of crime scene reconstruction or preservation when they arrive and instead are driven by the idea of "make it safe" so firearms are often found with no magazine, slide locked to the rear, and a loose cartridge laying next to it in the trunk of a patrol car. - The investigator can only work with what they have.

Cyanoacrylate fuming

- This method provides a leg up in fingerprint processing to many smaller police agencies who lack significant resources as a useful setup can be "home made" with commonly available items and the ongoing cost to use is very cheap. - This allows an agency to work their own evidence much faster than relying on a state crime lab or other assisting agencies.

Fingerprints as a Means of Identification

- Though fingerprints are only one form of biometric identification, they currently offer dramatic advantages to the others on a large scale. - Given they are the oldest form, standards have been actively gathered for a very long term. - As a result, the searchable database is incomparable to others. - This is on its own a substantial advantage however the availability to use the discipline is much broader reaching. - The resources necessary to capitalize on a fingerprint recovered from a crime scene or an unidentified decedent are readily accessible through local law enforcement across the nation and world. - While DNA may be the closest comparable means of identification to fingerprints there are significant differences which can be quite substantial on a case by case basis. - Fingerprint work can progress quite rapidly, and identifications can be obtained within minutes under the right circumstances thanks to the local resources. - In contrast, DNA work is often accessed through a larger regional agency and if conducted in-house by a large law enforcement agency still requires significant time to progress through its steps.

Firearm Ammunition

- Though much misinformation floats around popular culture about firearms in general, no area of this topic is this more true than with ammunition. - The terminology is misused so commonly by even credible professionals it can be quite difficult to maintain consistency. - The projectile which exits the muzzle of the firearm and is propelled at great velocity towards a target is called by many names: bullet, round, shot, projectile. The same is true of the remnants of firing. - The cartridge case which previously held the propellant, primer, and projectile after being fired is now ejected from a semi-automatic weapon and discarded onto the ground. - It is referred to mistakenly as the bullet, round, shell, and so on. - The newly purchased package of ammunition off the shelf from the store contains cartridges. - This is true of handgun or rifle ammunition. - The ammunition fired by a shotgun is a variation of this.

Firearm Propellants and Powders

- Though not referred to in the text an area of firearms awareness which can prove useful through this education in powder composition is the practice of reloading. - Many private individuals collect spent shell cases from the firearms range and reload them with new primers, propellent, and press in a new projectile. - This can be a highly variable process depending on the level of expertise or lack thereof in the individual performing the reload. - The results can be benign or catastrophic firearm malfunction.

Forensic Serology / 4.1.2 Blood

- Though often mistaken for the study of blood, this branch of forensic science is responsible for other components from the body as well. - Though blood may often prove to be the most useful in a forensic setting, the analysis of seminal and other fluids can be probative in court as well. - Amongst the complexity of a full discussion about the science of these studies, within a course centered around investigation let us touch on the confirmatory methods and what the lab personnel can tell us. - The first step to analyzing a sample of blood is to be certain or relatively certain it is blood. - Though most experienced professionals in the field can appreciate the subtleties about the specific color or physical properties of blood, laboratory personnel must adhere to strict guidelines concerning the accreditation standards set forth. - A popular method of presumptive testing for blood is the use of phonelphthalein, or the Kastle-Meyer test. This oxidizing reaction provides an immediate and distinctive color change which indicates a positive. - The bright pink color is readily identifiable and works well, but consider the need with the big picture. - Sampling some of the material in order to test is consuming some of it. - Might it be the better strategy to simply forego the confirmatory test and go straight to DNA analysis. - If a minute amount is collected in the field because of a substantial cleanup effort made by the suspect, and a presumptive test is conducted, there may be nothing left to analyze for DNA. - The best case scenario end result for analysis of blood today is an identifiable DNA profile.

Bloody fingerprint development

- Though the text characterizes all bloody fingerprints as patent, refer to the following discussion and figures. - This is an image of a high gloss white floor tile which was thoroughly cleaned and dried, then handled with bloody fingers. - There are areas that feature obvious ridge detail. n this figure the same tile has been sprayed with water-based amido black. - Looking closely you can already see very clear ridge detail forming in the center of the tile - In this figure the same tile has been sprayed with water-based amido black. - Looking closely you can already see very clear ridge detail forming in the center of the tile - Here is the final product after the amido black was sprayed to maximum contrast then rinsed with clean water and the tile allowed to dry. - In taking the time to compare the first image with the last in this series one should immediately learn identifiable fingerprints in blood can be present and not all visible to the eye.

What Fingerprints Are

- Through our own growth and exploration everyone has discovered they possess fingerprints. - This awareness even helps the crime scene investigator or fingerprint analyst testifying in court to connect with a jury by explaining the more in depth aspects to them using their own demonstrative aids. -This concept continues into 13.3 Fingerprint Patterns as well. The uniqueness of fingerprints shows its power when considering identical twins share the same DNA profile, however they do not share the same or even similar fingerprints. - This fact enduring through one's lifetime is one of the principles of the power of fingerprints.

Recognition, Collection, and Preservation of Fingerprint Evidence

- To build upon the text, let me stress that greater results in a fingerprinting effort will always be obtained if the item is able to be collected and brought back to a controlled setting such as a lab in order to be exploited for fingerprints. - This is true providing it is collected and transported in such a manner which won't destroy fingerprints on its surfaces. - The stressors of being in the environment have an effect on the work quality by impacting one's attention level, attention span, and by introducing distractions as well as performance stressors when being watched. - Also not to be discounted is the value in physical comfort when performing delicate work such as fingerprinting. - If the means reasonably exist to collect evidence to be fingerprinted later, wisdom suggests you do so.

Urine

- Urine is not generally of great forensic significance as it is not a great carrier of DNA material however vaginal secretions can be as probative as other fluids previously discussed, again relying on identification of the source in order to establish the appropriateness or not of the presence of DNA. - The importance of identifying the source must be considered as verifying it can consume a significant portion of the sample prior to DNA testing.

Drugs and Poisons as Biological Evidence

- We have by now familiarized ourselves with the term forensic and should be able to apply it to many pre-existing scientific disciplines. - Within this chapter, we'll focus on the toxicologist in a forensic setting. Chapter 11 will deal with a related but different specialty, seized drug analysts.

Clandestine Drug Laboratories

- We wrap up our discussion on toxicology overall by looking into the phenomenon of clandestine drug laboratories which are encountered in almost every imaginable scenario within our communities. - Ranging from the small "one-pot" method using only one vessel requiring constant attention to the more elaborate multi-stage process contained in a house, apartment, or other various structure. - The majority of these operations are currently making methamphetamine, or "meth", because of its relative ease and simplicity of ingredients. - The most important educational point in an overview study of these labs must be to stress their hazardous nature compared to the other topics we have discussed. - Apart from the toxicity of the substances involved, depending on the stage of activity there may be quite flammable or explosive potential even spontaneously. - Specially trained persons should be utilized to dismantle such laboratories and render them safe prior to analysis and collection.

Firearms

- Whether or not your personal interests draw you to seek a familiarity with firearms the needs of a forensic investigation job require it. - The knowledge serves the investigation by knowing what evidence to look for and what the absence of some evidence may mean. - For example, are there spent shell cases at the scene of a shooting? - If not, was a revolver used which does not eject its spent casings or did the shooter take the time to collect the spent casings from the ground? - The knowledge also serves the court process as the expert witness is in a position to explain scene findings to the jury which are often laymen in specific terms of firearm function. The textbook walks through the differences between handguns, divided into revolvers and semi-automatic pistols, and long guns, such as rifles and shotguns. - Though it may seem vague, the text may capture what is the most accurate actual definition of the phrase "assault rifle" by using the term "automatic" instead of "semi-automatic". - This distinction is broadly misused in popular culture today and the source of heated political debate. - The automatic military style rifles are characterized by their ability to fire cartridges continuously and rapidly as long as the trigger is depressed. - The semi-automatic firearm, whether a handgun or long gun, fires one cartridge each time the trigger is pressed.

Inheritance of DNA Characteristics

- While a complete understanding of DNA analysis is impossible in an overview, there is power in having a basic understanding of important facets of the work. - The definition often given of DNA is simple as well, the genetic blueprint of life, however it still doesn't tell you what DNA stands for. - As you should be aware by now this class contains a lot of information from many directions, all pointing towards one goal, the name of the class. - When we investigate something forensically we intend to explain our findings to a jury. - If you have to explain to a jury something about DNA, I suggest you start with telling them what it stands for. - Do you know? - Deoxyribonucleic Acid. Don't be caught speechless by a defense attorney on an easy question. - The information contained in the DNA, instructions for growth and development is received in equal portions from your mother and father, and a useful portion of this information remains unique to you throughout your life.

DNA Typing

- With this subsection, we begin to appreciate the complexity of DNA analysis and are perhaps humbled by those who specialize in the craft. - As said earlier, for professionals working in the investigative field it is important to know enough about the process of DNA analysis in order to responsibly request the labor and be able to explain to the layman the steps involved. - Within this portion, we begin to understand the portion of the genome that is used for identification as short tandem repeats (STRs) are mentioned.