Forensics 100 Part 3

impressed toolmarks

(also called compression marks) - produced when a tool is placed against another object and sufficient force is applied to the tool to leave an impression. These impressions are contour variations left on the surface of the object by this interaction.

striated toolmarks

(also called striae, friction marks, abrasion marks, or scratch marks) - produced when a tool is placed against another object and moved parallel to and across the object with pressure applied. The striations consist of the resulting surface contour variations.

cast

1. A method of making a mold by first making a three-dimensional model of a shoe or tire and then forming the mold from that model. 2. The filling of a three-dimensional footwear or tire track impression with material that takes on and retains the characteristics that were left in that impression by the footwear or tire. 3. A method used in the lifting of two-dimensional footwear and/or tire impressions from rough surfaces.

postmortem or facial reconstruction

Being a reconstructionist involves the rebuilding of facial features of unidentified badly decomposed or skeletal human remains. These images are created digitally, by sketching or three-dimensionally with clay. They are used for identification. Additionally postmortem drawings are also reconstruction images. These are the facial drawings created by viewing photographs or the remains themselves of an unknown deceased person. In these cases the bodies are relatively intact and not as decomposed. These drawings are used for identification.

breech marks

By far the most common impressed action marks on cartridge cases are breech marks. Most fired cartridge cases are identified as having been fired by a specific firearm through the identification of breech marks. Very high pressures are generated within a firearm when a cartridge is discharged. These pressures force the bullet from the cartridge case and down the barrel at very high velocities. When a firearm is discharged, the shooter will feel the firearm jump rearward. This rearward movement of the firearm is called recoil. Recoil is for the most part caused by the cartridge case moving rearward as an opposite reaction to the pressures generated to force the bullet down the barrel. When the head or base of the cartridge case moves rearward, it strikes what is called the breech face of the firearm. The breech face rests against the head of the cartridge case and holds the cartridge case in the chamber of the firearm. When the head of a cartridge case slams against the breech face, the negative impression of any imperfections in the breech face are stamped into either the primer of the cartridge case or the cartridge case itself.

father of toxicology

16th century scientist Paracelsus - credited for the idea that the dose makes the poison - any substance, in sufficient quantity, can and will have an adverse effect on the body

modern father of toxicology

19th century scientist Mathieu Orfila - wrote a treatise on poisons that is still referenced today and became a professor of medical jurisprudence - a forensic doctor - in Paris. He was considered the preeminent authority on poisonings and was called in to testify as a medical expert in many cases.

how many strs in following sequence? CATACATACAT

2.3

nucelotides

A, T, C, and G - There are loose, individual nucleotide molecules added to the solution. The polymerase grabs on to the nucleotide molecules floating around in the solution, one at a time, and binds them to the nitrogenous base sticking out from the DNA backbone. Each new nucleotide is added to the DNA strand until the template strand is duplicated, essentially copying the DNA so one single strand has now become a double helix again. This is the chain reaction part of the polymerase chain reaction.

four FBI ancestral/population groups

African American (AA), which generally includes people of African descent Caucasian (CAU), which generally includes people of Asian and European descent Southwest Hispanic (SWH), which generally includes people of Central America Southeast Hispanic(SEH), which generally includes people of South America and the islands south of Florida

class - synthetic drugs

Agitation, irritability, impaired perception of reality, reduced motor control, inability to think clearly

is it human?

All mammals share a generalized skeletal template, meaning they all have the same bones in roughly the same locations: a skull, spine (which ends in a tail), ribs (which support the internal organs), and four sets of limb bones. However, the shape of the bones and the way they relate to each other, differ between animals. By examining the size, shape, and structure of a bone, an anthropologist can determine if it is human

class - hallucinogens

Altered perception and mood, mild to severe hallucinations

dna interpretation

An electropherogram is the way that DNA analysis data is given by the CE

extractor marks

Another action mark, usually found in a striated form, are those created by the extractor of most auto-loading or repeating firearms. The extractor is a small part sometimes resembling a hook that is used to remove a cartridge or cartridge case from the chamber of a firearm.

shear marks

Another common striated action mark are shear marks produced by GLOCK pistols on cartridge case primers.

wear

As shoes and tires are used, their physical features change over time

ejector marks

As the cartridge case is pulled to the rear it will be struck somewhere on an opposing edge by a part as seen below called the ejector. The ejector is designed to expel the cartridge case from the action of the firearm. The resulting impact of the cartridge case with the ejector will cause another action mark that can be used as a means of identification. impressed

AFTE

Association of Firearm and Toolmark Examiners

gelatin lifter

a sheet of rubber with a low-adhesive gelatin layer on one side that can lift prints from almost any surface, including porous, rough, curved and textured surfaces. It is less tacky and more flexible than an adhesive lifter, allowing it to pick up a dusty shoeprint on a cardboard box, for example, but not tear the surface of the box.

impression

a shoe mark in sand

polymerase

a special protein whose job is to latch on to a DNA strand and make a copy. Copies are only made when the DNA double helix has been split down the middle and the two DNA strands that made up the helix are separated into single stranded DNA.

illegal drug

a substance that causes addiction, habituation, or a marked change in consciousness, has limited or no medical use and is listed on one of the five schedules within the U.S.C. Controlled Substances Act. These schedules include drugs such as cocaine, heroin, methamphetamines, certain prescription drugs, and marijuana, among many others.

plastic print

a three-dimensional impression left on a soft surface. This includes shoe or tire tracks left in sand, mud or snow.

Electrostatic dust-print lifting device

a tool that electrostatically charges particles within dust or light soil, which are then attracted and bonded to a lifting film. This method is best for collecting dry or dusty residue impressions on almost any surface, even the skin of a cadaver.

visible print

a transfer of material from the shoe or tire to the surface. This type can be seen by the naked eye without additional aids.

there is not

always dna present, dna does not last forever

component of a system to be analyzed

analyte

dna analysis

analyzing all of these DNA fragments so we can tell how many STRs (short tandem repeats) there are in the alleles at each of the loci. The instrument that analyzes the amplified DNA is the capillary electrophoresis (CE),

firearms

anything having to do with guns, bullets, or any firearms paraphernalia like silencers or suppressors.

firing pin impressions

are indentations created when the firing pin of a firearm strikes the primer of centerfire cartridge case or the rim of a rimfire cartridge case. If the nose of the firing pin has manufacturing imperfections or damage, these potentially unique characteristics can be impressed into the metal of the primer or rim of the cartridge case.

firearms and ballistics

are not the same thing

individual characteristics

are unique aspects of a particular shoe or tire that result from use, not the manufacturing process. These could be from damage such as a cut, gouge or crack, or a temporary alteration like a stone or twig stuck in the tread.

breech and firing pin impressions can

be used to associate spent ammunition with the weapon from which is was fired

to destroy lingering DNA

bleach or alcohol

pistols

can be held and fired with one hand

is it bone?

can be mistaken for bone: Ceramic shards, plastic, wood fragments, rocks, small bits of concrete can all be mistaken for bones or bone fragments. To ensure the material is bone, the anthropologist cleans the object and examines it closely, under magnification if necessary.

forensic drug chemistry

chemistry as it is applied to the identification of illegal substances within the criminal justice system.

three main characteristics to analyze imprints

class, individual and wear

three main disciplines of forensic artists

composite art or imagery, postmortem or facial reconstruction, and image modification and enhancement.

microscopic hairs found on marijuana leaves

cystoliths

forensic toxicology

deals with the application of toxicology to cases and issues where those adverse effects have administrative or medico‐ legal consequences, and where the results are likely to be used in court.

cycles of PCR process

denaturing annealing extending

rifles

designed to be shoulder mounted (or rested on a bipod, tripod, or bench rest) and fired with two hands.

presumptive testing or screening

determines the general characteristics of the sample material and allows analysts to narrow down the field of confirmatory tests that will be used. Presumptive laboratory tests may include: microscopic analysis, microcrystalline test, ultraviolet spectroscopy, and gas chromatography

weight test

determines the net weight of the material. Evidence submitted can range from residue on a surface to stains on fabric to pounds or tons of seized material. Analysts use analytical balances to weigh the material and record the results for the analysis report. The weight test will also determine if the quantity of material is sufficient for further testing.

salt is chemically coupled to many plant-based drugs to make them

dissolvable

microcrystalline test

dissolving a small amount of the sample in a solution and letting the material form crystals. Substances will crystallize in a specific manner allowing analysts to identify components of a sample by viewing the crystals under polarized light.

nearly all police departments

do NOT have at least one forensic or police sketch artist on staff

EMIT

enzyme multiplied immunoassay technique - a way to rapidly screen blood and urine for the presence of common drugs - screening test

drug schedules

establish penalties for the possession, use or distribution of illegal drugs. Substances are scheduled depending on their potency, potential for abuse, likelihood of physical dependency, and legitimate medical use

impression evidence

evidence that is created when an items leaves its mark on another item in the form of scratches, indents, depressions, etc. part of the impression evidence lab: Fingerprints Shoe or footprints Tire tracks Toolmarks Firearms

determine sex of skeleton

examine pelvis and skull

striations

fine horizontal scratches etched onto a bullet after it has been fired

marsh test

first use of toxicology in a jury trial - tests for arsenic

shape of crystals formed when mixing pure cocaine with platinic chloride

flat molars

ftc

forensic toxicology council

screening process

functions as a massive elimination process when finished with the screening, no drugs will be identified but a lot of chemicals will be eliminated

prints

imprints - a bloody shoe print on concrete

toxicology

is the study of the adverse effects of drugs and chemicals on biological systems.

excipients

inert bulking agents added to drugs to increase their weght

breath alcohol measurement

is done by sampling the deep, alveolar air

the amelogenin locus that indicated whether the dna is female or male

is in the red channel, called AMEL

presumptive tests

less precise drug may be present can be conducted by officer in the field is usually colorimetric, meaning the test will indicate that the suspected substance is present or not present by changing color. If the substance is present, the test kit will turn one color, if not, it turns a different color. Presumptive testing by law enforcement is typically followed up with laboratory tests that confirm with certainty the presence of the suspected substance. Presumptive testing is also performed in the laboratory as part of the analysis process.

toxicology

looking for minute quantities of drugs in body tissue or fluids

microscopic analysis

looks at the structure of the material to make a preliminary estimate as to what it may be. This test is most suitable to plant material.

individual characteristics (firearms)

marks produced by the random imperfections or irregularities of tool surfaces. These random imperfections or irregularities are produced incidental to manufacture and/or caused by use, corrosion, or damage. They are unique to that tool and distinguish it from all other tools.

gas chromatography

may provide presumptive identification of materials, but is commonly used to separate components prior to confirmatory testing.

stature of a skeleton is determined by

measuring arms and legs

two different primers added to PCR solution

one primer marks the locus to get copied on one strand and the second primer marks the locus to get copied on the other strand.

latent print

one that is not readily visible to the naked eye. This type is created through static charges between the sole or tread and the surface.

class characteristis

result from the manufacturing process and are divided into general and limited. General class characteristics include those that are standard for every item of that make and model. Limited characteristics refer to variations that are unique to a certain mold.

wear characteristics

result from the natural erosion of the shoe or tread caused by use. Specific wear characteristics include the wear pattern, the basic position of tread wear; the wear condition, the amount or depth of the wear; and where extreme, the damage to or destruction of the tread.

revolvers

revolvers do not automatically expel the cartridge from the weapon after each round has been fired. Revolvers also do not have a magazine to hold cartridges; instead, revolvers have a cylinder with individual chambers into which cartridges must be loaded. After firing all of the ammunition in the firearm, the cylinder must be popped out, manually emptied, reloaded, and then popped back in to the firing position.

bullet shapes

round nosed lead bullet and the full-metal-jacketed bullet.

comparison microscope

two stereo microscopes connected by a special tower that allows the user to view the images together, compare them side by side, and overlay them.

class - narcotics

General sense of well-being, drowsiness, inability to concentrate

class - inhalants

Loss of inhibition, intoxication, slurred speech, decreased coordination, euphoria, disorientation

class - steriods

Mood swings, hostility, impaired judgment, aggression

denaturing

The DNA gets heated up to 95 degrees C (203 degrees F - just below boiling). This high temperature causes the bonds between the bases of the DNA in the double helix to melt (break apart), so the double DNA strands separate into two single strands.

extending

The DNA is heated to 72 degrees C (161 degrees F), which is an ideal temperature for the polymerase to do it's job of copying the DNA strands as quickly as possible. When the polymerase comes to the end of the DNA strand, it falls off the end and waits until the next cycle begins to start the copying process over again.

annealing

The DNA then gets cooled down to 50-72 degrees C (122-161 degrees F). This cooler temperature allows the primers to bond to the DNA at their specific locus. As soon as the primer attaches, it signals to a polymerase to attach and get ready to copy.

PCR - Polymerase Chain Reaction

The PCR process was invented by an American scientist named Kary Mullis. The purpose of using PCR is to take the small amount of DNA you have in your sample - modern forensics can produce a DNA profile using the DNA from as few as 4-6 cells - and turn those few strands of DNA into millions or billions of exact copies.

SWGTREAD

The Scientific Working Group on Shoeprint and Tire Tread Evidence

Amplification

The amplification process works using the same PCR process in the same thermal cycler with one major exception: The primers for the different CODIS loci have different color fluorescent tags on them - red, yellow, green, or blue - and these tags are used to help tell the different DNA sequences apart during analysis.

reading an e-gram

The boxes on the top name the chromosome and the locus number The numbers underneath the boxes, 100, 150, 200, etc., are the number of base pair lengths the fragment is. Notice that within each locus there are multiple peaks that represent longer or shorter fragments - these are the alleles. The number of STRs per allele determines whether a DNA fragment at a locus is shorter or longer than another. The peaks are different heights as well - the higher the peak, the greater the abundance of DNA fragments at that base pair length was in the sample.

pathology

The field of study concerning the causes and processes of disease.

image modification or enhancement

This area of forensic art involves the alteration or enhancement of a photograph or image of a person for the purpose of updating, clarifying or identifying a subject. Age progressions and age regressions are image modifications. These images can be drawn or done as digital images. This type of work is often used in missing person cases - especially cold cases involving children who will have aged significantly since they went missing - and for criminal cold cases where the suspect(s) may have aged several years since committing the crime.

composite art or imagery

This is the technique of creating a sketch of an unknown subject from individually described parts into a single graphic image. It is intended to be a likeness or similarity of a victim's or witness's perception of the subject at the time the subject was seen.

firing pin drag marks

When the firing pin springs forward to strike the primer of a cartridge, it may remain slightly forward and imbedded in the primer.

how a gun works

When the trigger is squeezed, the firing pin pulls back and then springs forward, impacting the back of the cartridge. This starts the chain reaction that results in a bullet leaving the gun (more on this below). Pistols are loaded using a magazine, which holds a certain number of rounds in the chamber (in the grip of the gun above). After each round if fired, the cartridge - now bullet free - is automatically expelled from the gun by an extractor (that grabs the edge of the cartridge case) and an ejector (that tips the case) so the cartridge case leaves the barrel of the weapon. This allows another cartridge to move into place so it can be fired.

database that compares the skull measurements of an unknown person to those measurements from skulls around the world

3D - ID

DOT number

Department of Transportation serial number assigned to every tire sold in the United States; it gives information regarding the manufacturer, size and date of manufacture of the tire.

class - marijuana

Euphoria or "high", altered sensory perception, sleepiness, disrupted coordination/balance

class - stimulants

Euphoria or "high", exhilaration, wakefulness, agitation, hostility, hallucinations

antemortem

If they are looking for substances in the samples from a live person, these samples are considered antemortem - literally translated to "before death."

semi-automatic vs fully-automatic

In a semi-automatic pistol, the trigger must be pulled every time the shooter wants to fire a bullet. In a fully-automatic (often just referred to as an automatic), the trigger can be held down indefinitely and the weapon will continue to fire until it runs out of ammunition. Fully automatic weapons tend to be military weapons and are often illegal for civilians to possess.

class characteristics (firearms)

Intentional or design characteristics that would be common to a particular group or family of items. The class characteristics of firearms that relate to the bullets fired from them includes the caliber of the firearm and the rifling pattern contained in the barrel of the firearm. Cartridges and Cartridge cases on the other hand are examined for class similarities in what are called breech marks, firing pin impressions, extractor marks, ejector marks and others.

IAI

International Association for Identification

what bones are present?

Once a case involves human bone, the investigator must identify which bones (or "elements") are present and which are absent. Most anthropologists start this process by placing the elements out on a table as they would be organized in a living person, known as the "anatomical position". This serves several purposes. First, it creates an informal visual inventory that allows any missing elements to be identified quickly. Also, it allows the analyst to work systematically through the entire skeleton, performing a detailed inventory and examining each bone for trauma, pathology, or life history traits. Lastly, after examining each bone, the analyst can consider the skeleton as a whole, and look for inconsistencies among elements or patterning of trauma across multiple elements.

chamber marks

One of the most common striated action marks are called chamber marks. Roughness in the chamber of a firearm can scratch the outer walls of a cartridge case when loaded and removed from the chamber. Most chamber marks occur after the cartridge is fired.

NEVER

PUT THE TOOL INTO THE TOOLMARK

schedule drugs numbers and definitions

Schedule I - no medical usage, high potential for abuse. Examples include Heroin, LSD, peyote, MDMA Schedule II - severely restricted medical usage, high potential for abuse, but slightly less than Schedule I drugs. Examples include cocaine, methamphetamine, methadone, oxycodone Schedule III - currently accepted medical usage, moderate potential for abuse, and moderate to low risk of dependence. Examples include barbiturates, steroids, ketamine Schedule IV - widely used for medical purposes, low potential for abuse and low risk of dependency. Examples include Xanax®, Valium®, tranquilizers Schedule V - widely used for medical purposes, very low potential for abuse, contain limited quantities of narcotics. Examples include Robitussin® AC, Tylenol® with Codeine

SWGTOX

Scientific Working Group for Forensic Toxicology

SWGDRUG

Scientific Working Group for the Analysis of Seized Drugs

class - depressants

Sleepiness, amnesia, impaired judgment, confusion, slurred speech, loss of motor coordination

firearms identification

The identification of fired bullets, cartridge cases or other ammunition components as having been fired from a specific firearm.

capillary electrophoresis (CE)

The job of the capillary electrophoresis is to separate the DNA strands from one another, shine a laser at them that causes their dye tag to glow its specified color, and then "count" the length of that fragment of DNA to determine which locus it belongs to

non-jacketed bullets

The most common material used in the manufacture of non-jacketed bullets is lead. Lead bullets are usually an alloy of lead and antimony which is added to give the bullet some additional hardness. Variations are the norm when it comes to the materials used in bullets and it's not uncommon to find lead bullets with a thin coating of copper or brass plating.

anatomical position

The position of a body so that it is lying on the back, with legs and arms spread and palms facing up. In this position, each bone is visible without any overlap and a visual inventory of the remains can be made.

quantitation

The purpose of quantitation is simply to see how much DNA we have in our sample. The reason we need to know is that the next step - amplification - requires that a certain amount of DNA be used in order for the process to work properly

pattern evidence

These footwear and tire track impressions are referred to as "pattern evidence" because the impressions form a unique pattern. Shoes and boots leave prints and impressions specific to their particular brand, style and size. The tread on each tire of a vehicle may provide investigators with similar information.

Integrated Ballistics Identification System (IBIS)

a computerized means of cataloging and acquiring digital images of firearms related evidence including fired bullets and cartridge cases

adhesive lifter

a heavy coating of adhesive lifts the imprint from smooth, non-delicate surfaces such as tile or hardwood floors, metal counters, etc. It is usually used in conjunction with fingerprint powders.

jacketed bullets

a layered combination of various materials to include lead, copper, brass, bronze, steel, and aluminum a laminate of material, with the harder "jacket" covering a core typically made of lead. This jacket material differs from the thin copper plating seen on the copper-washed bullets above. The jacket material cannot be easily removed.

firearm

a portable gun - a barreled weapon that launches one or more projectiles, often driven by the action of an explosive force..

primers

a primer is a special marker. It is a short DNA strand with a pre-determined sequence of bases, usually 20 bases long. During the PCR process, the double strand of DNA gets unzipped into two single strands of DNA, leaving the bases sticking out from the backbone exposed. The bases of the primer bond to the now-available bases on the single strand of DNA. Once the primer binds to the DNA strand, it acts as a signal for the polymerase copy machine to attach to the DNA and start copying the strand.

GSR

gunshot residue

shotguns

have no rifling in the barrel and (mostly) shoot more than one projectile at a time. They look similar to rifles, but they are much less precise and accurate by design. These shotguns are designed to be shoulder mounted and fired with two hands.

parts of a cartidge

he primer, the propellant, the case, and the bullet. The primer is at the rear of the cartridge - it is the point where the firing pin inside the gun barrel (see diagram above) strikes the cartridge and initiates a spark. The spark ignites the propellant, which is usually some type of gun powder. The rapid burn of the propellant causes a huge pressure build-up in the cartridge case, and in order to release the pressure, the bullet bursts off the front of the cartridge case, where it flies down the barrel at high rate of speed and exits the weapon out the barrel.

website with forensic drug chem terms

http://www.forensicsciencesimplified.org/drugs/glossary.html

not one of the considerations drugs analysts wrestle with while performing examinations of drug evidence

physiological effect

ingredients added to buffer solution that gets added to DNA

polymerase primers nucelotides

cutting

practice of mixing a pure drug with other substances to make the drug less potent

two types of tests used to determine whether an illegal drug is present in a substance

presumptive and confirmatory

confirmatory test

provides positive identification of substance requires a lab and instruments uses instrumental analysis to positively identify the contents of submitted material. This typically requires a multi-step process to separate the individual compounds, determine the chemical characteristics of the compounds, and compare them against reference materials to make a positive identification. This is called qualitative analysis, and determines what substances are present and if one of more of those substances is illegal.

three step approach to drug identification

screening identification confirmation test

confirmatory testing

separation and identification of the individual components of the material. Confirmatory testing is usually a two-step process by which the analyst first separates the compounds using a suitable method such as gas chromatography (GC), capillary electrophoresis, or wet chemistry. Once the components are separated, instruments such as a mass spectrometer (MS) or infrared spectrometer (IR) are used to identify each component by comparing its chemical signature against reference materials.

ammunition that goes into a shotgun

shell

common street name for synthetic marijuana

spice

two types of toolmarks

striated and impressed

ballistics

subset of firearms. Ballistics refers specifically to the projectile once it has left the weapon.

drug

substance, other than food, taken to produce some effect on the body. The effect can be good or bad. all drugs have a desired effect and one or more side effects

photos

taken at 90 degree angle exactly

forensic anthropology

the application of the science of physical or biological anthropology to the legal process

forensic artist

the artistic technique used in the identification, apprehension, or conviction of a wanted person. This person may not necessarily be a criminal, but could be a missing person or an unidentified deceased person. These forensic images can be admissible in a court of law.

rifling

the gently twisting groove pattern scribed into a gun barrel to cause the bullet to spin as it leaves the barrel, adding to ballistic stability and accuracy.

alveoli

the tiny sacs in the lungs that allow the exchange of oxygen and carbon dioxide in the blood

goal of forensic chemistry

to determine whether the material submitted contains an illegal substance. Based on the results of the analysis, law enforcement can pursue criminal charges and the court can determine appropriate sentencing.

muzzle to target determinations are used

to help establish how far away the shooter was from the person or thing that was shot

measurements

toxicology - grams and milliliters drugs - micro grams and micro liters

twist

whether the bullet has a right hand or left hand spin as the bullet leaves the gun

signs of aging do not inlcude

whitening of teeth

ultraviolet spectroscopy

works by exposing the material to UV light and measuring the way the material absorbs the light. Different chemicals absorb light differently and can give clues to analysts about what might be present in the material.