FIVS123

Automotive paints, Structural, and artistic paint. evidentiary value

---Automotive paints: This type of paint formed the focus of your readings. Automotive paints are the paints used to coat the car. Most cars have four coats within the paint finished when first manufactured. Two coats of rust proofing are applied first. This is followed by the primer. The topcoat is next; this is the layer of paint that gives the car it's color. The final layer is the clearcoat that imparts extra durability and ultraviolet light resistance. Each coat of paint forms a layer to the paint job that can be analyzed in the event of accidents or other crime scenes involving vehicles. ---Structural paints: These are the paints used to paint buildings as well as other building objects. These paints usually consist of only one layer of paint, making physical analysis more difficult. However, because the layers of paint tend to be relatively thick compared to the application of automotive paints, the chances of finding a paint chip large enough to fracture match is increased, though the situation is still rare. ---Artistic paints: These are the oldest types of paints. In terms of forensic analysis, these paints are most often viewed in cases of artistic forgery. There are also other non-paint coatings that you might encounter, including shellac, varnish, and stains. Evidentiary Value Paint evidence is class evidence. Many car paint jobs will be too similar, chemically and physically, to distinguish. In rare cases, a large paint chip may be fracture matched back to the original spot. Structural paints usually consist of only one layer of paint, making physical analysis more difficult. However, because the layers of paint tend to be thin, the chances of finding a paint chip large enough to fracture match is increased, though the situation is still rare.

fingerprint dusting or fuming on smooth and fine surfaces.

-Fingerprint dusting and fuming can be used to localize and visualize latent prints in one step or to use as a second step after the print has been localized with an FLS. The usage of the various methods we just described, depends on the surface. Smooth, nonporous surfaces can be easily powdered or fumed as with the CA method. On very fine surfaces, or surfaces that are porous or have cracks and are nonmetallic, magnetic powders are better. The brush is moved across the surface without touching it; the powder clings to the surface of the fingerprint residue but not the cracks in the surface. A good fuming method for porous surfaces is the ninhydrin method.

Fingerprint ridge characteristics (value of fingerprints)

-Fingerprint ridge characteristics are considered to be individual evidence. -Fingerprints allow investigators to compare them to fingerprint images taken from a suspect in a criminal investigation. Identifying a fingerprint or area of friction ridge skin to a suspect in a criminal investigation provides proof of the following: ---The suspect touched the item on which the print was developed ---The suspect was at the same location as the item or area containing the print

Fingerprint comparison

-There are two types of fingerprint comparison. The first one is to identify a particular person from his or her fingerprints. For that a whole set of prints is taken and then compared with prints that are in fingerprint databases. The second one is when only partial fingerprints are available, as for example at a crime scene. They can be matched to a set of known prints when there are enough ridges available.

Patent Fingerprint

-are deposited in blood, grease, dirt, or fresh paint on a surface and are readily visible.

Plastic Fingerprint

-are formed in a soft material such as putty, wax, clay, or butter.

Latent Fingerprint

-are usually invisible. Pores, that form on the fingerprint ridges, release waste materials such as sweat, oils, proteins, fats, and other materials. When the finger touches a surface, these wastes are deposited, forming a fingerprint pattern that matches the friction ridge pattern of the individual.

Firearm characteristics

-sizing -rifling -firearm categories

EVIDENCE EXAMINATION You are acting as the firearms examiner for a case involving a fatal shooting at a nightclub. What components would you need to examine (or have examined by another expert) and in what order should the examination occur? Drag and drop your choices onto the clipboard in order. Then, click Submit. Note that not all choices will be used. If you cannot operate this interaction, click here to view an alternative version. You are acting as the firearms examiner for a case involving a fatal shooting at a nightclub. What components would you need to examine (or have examined by another expert) and in what order should the examination occur?

1) trace evidence on the firearm 2) DNA on the firearm 3) Latent Prints on the firearm 4) Bullet/casing class characteristics 5) Bullet/casing individual characteristics

Firearm categories

1. Pistols 2. Rifles 3. Machine Guns 4.Sub-Machine Guns 5. Shotguns

A live round

A live round consists of the bullet, the gunpowder (and primer), and the cartridge casing.

What is questioned document?

A questioned document is any written or printed communication between individuals whose source or authenticity is in doubt. Remember that documents are unique in that they are subject to the best evidence rule; the original document must be examined and admitted to court.

Tire Tread

A tire tread is part of the tire that makes contact with the road. Tires are designed today to provide gripping power and channel water to prevent hydroplaning. Tires are mass produced with only few unique or individual characteristics. With time and wear, tires pick up details that set them apart from other tires and change them from class to individual evidence. As with footprint impressions, many crime scene investigators overlook tire marks even though 2/3 of crimes involve cars.

Introduction of tool marks (analysis of tool marks as a part of firearms ID)

A toolmark is a scratch or other microscopic marking created when two metal objects come into contact with each other. Your readings focused mainly on the analysis of toolmarks as a part of firearms identification. The science of firearms identification covers a number of related disciplines: Bullets and cartridge cases can be traced back to a particular weapon Examiners can determine whether a particular weapon can be fired Examiners can estimate the distance between the gun, when fired, and its target Serial numbers can be restored on firearms and other objects Examiners also work with forensic pathologists in the area of wound ballistics, the study of the pattern of injury caused by firearm projectiles

Tear match (only way to individualize a fiber evidence)

Actually, there is ONLY one way to individualize fiber evidence: a tear match. A tear match fits a piece of torn fiber evidence back to its source, like a puzzle piece. This is the only way to individualize fiber evidence.

Drugs in the body: 3: Circulation

After being absorbed, ethanol circulates throughout the body, eventually reaching the outer surfaces of the brain. As BAC rises, alcohol begins to penetrate the inner parts of the brain, affecting vision and speech, balance, judgment, and at the highest concentrations, even affecting involuntary actions like breathing. Because ethanol penetrates several other organs and parts of the body, forensic toxicologists can use spinal fluid, eye fluid, urine, and sometimes even brain tissue to obtain BAC equivalents.

Photographed all footwear impressions...

All footwear impressions must be photographed at the scene, using a ruler or other measuring tool as a reference object. Footwear evidence can be fragile, so you must preserve it. Preservation depends on the type of impression. Click on each of the two types below to learn more about it: Two-dimensional impression preservation: For two-dimensional footprint impressions, photography is used. Make sure you photograph the footprint with a ruler or measuring tool. The camera should be parallel or 90° to the impression. Make sure the print is well lit. Use the camera flash. When using an extra light source, such as a flashlight, hold it 4-5 feet away from the print to avoid uneven lighting. Three-dimensional impression preservation: Three-dimensional footprints are cast using materials that fill the impression and then harden to capture an impression image. Photographs are a good tool to supplement the cast to provide the most information possible and should always be taken before the cast. Today, the universal product for making footwear casts is dental stone.

1883

Alphonse Bertillion, a French police expert, devised the first systematic method of personal identification in 1883. His method, known as anthropometry, included a detailed description and precise measurements of the body, including full length photographs. His system failed in 1903 when it was discovered that a new prisoner had the exact same body measurements as an already existing one.

1892

Alphonse Bertillion, a French police expert, devised the first systematic method of personal identification in 1883. His method, known as anthropometry, included a detailed description and precise measurements of the body, including full length photographs. His system failed in 1903 when it was discovered that a new prisoner had the exact same body measurements as an already existing one.

Arches

Arches have no delta. The arch patterns differ in severity of the slope of the arch. Arches make up only 5% of all fingerprint patterns. There are two different arch patterns: Plain Arch: Plain arches have gently sloping ridges. The top of the ridge is not pointy, but rather rounded. Tented Arch: Tented arches have a very pointy, nearly vertical slope. They resemble the shape of a tent, hence the name tented arch.

Glass as evidence

As forensic evidence, glass may not always be probative. However, it remains important because it is so pervasive and can often be carried away from the scene undetected. Glass is also stable evidence, as it does not decay under normal circumstances, and can be a valuable part of a pool of evidence used to build a case.

A closer look

As you learned, the live round for a rifled weapon is made of the bullet, the gunpowder, and the casing. As a firearms examiner, part of your job would involve examining fired rounds for the evidence that is left behind. Much of this evidence is in the form of toolmarks made by the firearm on the bullet and cartridge case in the process of firing.

Evaluation

At the third stage of the ACE-V method, the evaluation, the examiner comes to a conclusion. This can be either one of the following three: Identification: The latent/developed print matches the inked print. Non-Identification: The latent/developed print does not match the inked print. Inconclusive: The comparison is inconclusive and no distinct decision can be made. This could be the case when a print is not of good quality or not enough comparison points have been found.

BAC Equations

BAC Equations Your readings focused on the equations that allowed you to calculate the volume of alcohol needed to achieve a given BAC: Volume equation for males: Volume = (weight X BAC) ÷ 3.78 Volume equation for females: Volume = (weight X BAC) ÷ 4.67 Widmark also developed an equation to calculate a person's BAC, given how much alcohol the person drank and the time that has passed since he or she drank it. Similar to the volume equation, this formula is not accurate in every case, because it assumes that all drinking is done on an empty stomach and it assumes the average alcohol elimination rate of .015; however, it can be used as a general guide. BAC equation: Liquid ounces of alcohol multiplied by 5.14 divided by weight multiplied by alcohol distribution ratio minus .015 multiplied by hours during which alcohol was eliminated from the bloodstream BAC = ((A x 5.14) ÷ (W x r) - (.015 x H) A stands for the liquid ounces of alcohol consumed. You will arrive at this figure by multiplying the number of liquid ounces in the total serving of alcohol by the percentage of alcohol in the beverage. For example, as your readings pointed out, a typical glass of wine is 12% ethanol with a serving size of 5 ounces. So if a person consumed two glasses of wine then 10 multiplied by 12% equals 1.2 ounces of ethanol consumed. W stands for the weight of the individual, in pounds. The r in the equation stands for the alcohol distribution ratio. For males, this ratio will be 0.73 and for females, 0.66. H stands for the hours during which elimination took place. This is usually the time span from the beginning of drinking to when the BAC calculation is made. Continue on to the next page to practice calculating a person's BAC in different scenarios.

Fracture matching

Because most glass is mass produced and lacks unique characteristics, it is considered class evidence. However, pieces large enough to be manipulated can be pieced back together like a puzzle. This fracture match characteristic is the only way to individualize glass to a common source. With float glass, which is very common in windows, for example, using ultraviolet (UV) light will reveal which side of the glass is facing up. This is an important first step in fracture matching float glass to ensure that all of the pieces are oriented the same way before trying to match them. In keeping with the puzzle analogy, orienting each of the fragments with the same side up is akin to making sure that each puzzle piece is image side up before attempting to construct the puzzle. Having puzzle pieces in different orientations makes it harder, if not impossible, to ensure that the pieces fit together properly.

What always comes first? CLASS OR INDIVIDUAL CHARACTERISTICS examined first?

Class must be examined first before individual characteristics

Iodine Fuming

Close this window. Oldest chemical method May be used on most surfaces but is corrosive with metals When iodine is heated, the iodine crystals sublimate to iodine gas Gas adheres to fats in the fingerprint residue; reaction forms a reddish-brown image of the print Print is only temporarily visual and needs to be photographed immediately

Cyanoacrylate Ester (CA)/ Super Glue fuming

Cyanoacrylate Ester (CA) method is also called Super Glue® fuming Is considered a pretreatment for developing latent prints; it is a fixative for latent prints Generally used on nonporous and semiporous items Fumes reacts with amino acids, proteins, and fatty acid residues; as the fumes adhere, they polymerize, hardening to a white color Durable print, can be treated with powders or other chemicals afterwards to increase contrast and visibility Most labs today have a Super Glue® fuming tank in which different types of evidence can be placed

Gunshots

Distance-of-fire determinations are done by test firing the same weapon and ammunition at various distances and comparing the size of the stippling and soot patterns. A contact shot occurs when the muzzle of the barrel is in direct contact with the target. Gunshot residue may be found inside the wound. When GSR is found on a target, that is considered a close range shot. A distance shot produces a roughly round shape of the bullet hole made. The edges of the hole may also be burned or singed due to the friction from the bullet passing through. No GSR will be found with a distance shot.

Role of Questioned Document Examiner

Document examiners compare unknown handwriting, typewriting, and other documentary evidence with known standards in an attempt to establish the origin or authenticity of the known materials. They also attempt to restore obliterated or damaged writing and analyze paper and inks. Remember that the questioned document examiner is not a graphologist. Graphologists claim to be able to discern personality characteristics by someone's handwriting. Graphologists are not permitted to become certified by the American Society of Questioned Document Examiners.

Drugs in the body: 1 :Intake

Drugs can be administered in a variety of ways, including: •liquids, •pills, •tablets, •powders, •injections, and •inhalation.

Analysis: Level 2

During the second level of detail of the analysis stage, the examiner observes the minutiae or individual characteristics in the developed print.

Drugs in the body: 5: Elimination

Ethanol can be sweated out and, being fairly volatile, can also be exhaled through the breath, allowing for the measurement of alcohol via breath alcohol concentration instruments. However, elimination via breath and sweat only account for about 5% of the total elimination. Most of the alcohol is eliminated through the urine after metabolism. The time interval it takes for the concentration of a drug to drop to half of its initial concentration is called its half-life. This decrease is caused mainly by metabolism and elimination.

Drugs in the body: 4: Metabolism

Ethanol eventually reaches the liver where it is metabolized, commonly into acetaldehyde and then to acetic acid, before being eliminated. In most people, the rate of metabolism is 0.015 percent/hour ±0.03. However, this rate is not accurate in all persons. A person has no control over the rate of metabolism of a substance. In many cases, a drug is metabolized so quickly that forensic scientists only look for known metabolites, the different substances which the liver breaks the parent drug into.

Drugs in the body: 2: Absorption

Ethanol is absorbed in both the stomach and the small intestine. Other drugs may be absorbed in different locations and at different rates, depending on how they were introduced. With the exception of drugs taken orally, a person has no control over how quickly a drug is absorbed. The effects of ethanol depends on the rate of absorption. There are two major factors influencing this rate: drink concentration and contents of the stomach.

Ethanol

Ethanol, the active ingredient in all liquor, wine, and beer, is a central nervous system depressant. It acts as a mild tranquilizer and a neurotoxin. Different alcoholic drinks have different concentrations of ethanol Liquor: In liquor, the concentration of ethanol is measured in proof, twice the volume percentage of ethanol. 100-proof whisky contains 50% alcohol by volume. Wine: In wine, ethanol is measured in volume percent. A typical wine contains 10% ethanol Beer: Ethanol in beer is also measured in volume percent. A typical beer contains about 5% ethanol.

Fiber analysis

Fibers can be analyzed both physically, with the use of a microscope, and chemically.

Footwear Impressions..... type of evidence and type of impression

Footwear impressions may be left at crime scenes, and in entry and exit locations of scenes. Footwear evidence can be easily overlooked and is generally undervalued by police, detectives, judges, and juries. Type of Evidence Impressions by new shoes without wear are considered class evidence. Shoes with wear and tear have imperfections, alterations, and random markings which make their impressions individual evidence. Type of Impression Trace evidence may be transferred from the shoe to the surface, also called positive impression. When trace evidence is transferred from the surface to the shoe, it is a negative impression.

What are friction ridges and what is their purpose?

Friction ridges are the series of hills (ridges) and valleys (furrows) on the skin of the hands and feet; their purpose is to provide a textured surface for gripping and holding on to objects.

Friction ridges do not only exist on fingers but also....

Friction ridges do not only exist on fingers but also on the palms of the hands, the soles of the feet, and even lips. In this course, we will mainly focus on fingerprints though.

how long does it take friction ridges to develop?

Friction ridges start to develop at 8-10 weeks of gestation and become fully developed by the seventeenth week. As the friction ridges develop, perspiration glands are formed and connect to pores in the epidermis.

300 Bc

From approximately 300 BC onward, the Chinese used fingerprints as a means of personal identification. There are no historical records addressing why they used fingerprints in these early times. However, the mere use of fingerprints indicates an intuitiveness concerning the distinctiveness of fingerprints as they relate to people.

What is glass?

Glass is a type of matter known as an amorphous solid. It has properties of both a solid and a liquid. The major ingredient in sand is silicon dioxide but most types of glass contain additives or special process to impart certain properties.

1880

In 1880, Dr. Henry Faulds, a Scottish missionary in Japan who was working in a hospital, published an article in the journal Nature concerning the possibility of identifying criminals by their fingerprints left at crime scenes. He used this to help the Tokyo police in a burglary investigation. Fauld eventually asked Charles Darwin to fund future research on the matter but Darwin passed on the appeal to his cousin Sir Frances Galton, who ended up not funding Fauld but seemed to have been taken up the idea.

DIGITAL IMAGING SYSTEMS FOR AMMUNITION

In 1997, the Federal Bureau of Investigation (FBI) and the Bureau of Alcohol, Tobacco, Firearms, and Explosives (BATF) combined their imaging systems (DRUGFIRE and IBIS, respectively) into the National Integrated Ballistic Information Network (NIBIN) that allows for searching of bullets and cartridge cases using the same system. With the development of such databases came the idea of ballistic fingerprinting where each new weapon would be test fired and the firing pin impressions and breech face marks recorded in a database that could be used for crime scene comparison, when no weapon was found. However, this program has not been widely implemented due to its cost, the difficulty of substantiating a paper trail, and the possibility that the impressions and breech face marks may change between the time of the new test fire and the time the gun was used in the crime.

1870

In the 1870s, William Herschel, British official, required palm prints and impressions of right index finger from locals in India for every contract he made. Again, there is no evidence that he had developed any systematic way of linking these handprints to a particular person.

Ink examination

Ink examination may be required in cases where the questioned document is suspected of containing writings made at different times as well as validating the date of an entire document. Ink samples from a questioned document must be taken carefully so as not to deface the document. Thin layer chromatography is often used to analyze the dyes and help distinguish inks that may, on the surface, look the same.

Dactyloscopy

Is the science of comparison of friction ridge structures such as fingerprints

Ridgeology:

Is the science of ridge analysis

Leaded Glass

Leaded glass is relatively rare, due to the lead oxide additive, which gives the glass a higher refractive index and causes the desired sparkle and the characteristic ping sound. It is found in crystal wine glasses, figurines, and paperweights.

Alcohol and the law

Legal Intoxication According to Texas Penal Code 49.01, intoxication is defined as a) not having the normal use of mental or physical faculties by reason of the introduction to alcohol, a controlled substance, a drug, a dangerous drug, a combination of two or more of those substances, or any other substance into the body or b) having an alcohol concentration of 0.08 or more. Breath Testing Instruments Most states use a breath-testing instrument to obtain alcohol level in the field. Breathalyzers work via an oxidation-reduction (redox) chemical reaction. The solution without alcohol starts out orange, as alcohol is introduced through the subject's breath, the solution turns green. A spectrophotometer is used to measure the loss of the orange color. Newer breath testing instruments use fuel cell technology. The alcohol introduced by the subject's breath produces electricity. In most cases, breath alcohol concentration is converted internally to BAC via a 210:1 ratio. Field Testing Many states also recognize the field sobriety testing program developed in California. This suite of three tests, walk and turn, stand on one foot, and horizontal gaze nystagmus, also document impaired behavior when the driver is stopped. This can be helpful, especially in cases where a stopped driver's BAC measures below the legal level of intoxication but the driver still exhibits signs of impaired behavior. It can also document the impairments exhibited by the ingestion of illicit drugs. Blood Alcohol Measurement Even though breath alcohol tests are admissible in court, many prosecutors require blood alcohol tests to measure BAC directly. Forensic toxicologists often use gas chromatography on blood samples of suspected intoxicated individuals and interpret the findings.

lifting tape

Lifting tape is used to transfer a developed latent print onto a fingerprint backing card. The most common types of tape include clear and frosted tape. Note: If the developed print could be compromised or destroyed by lifting the print, the print should be photographed prior to lifting attempts. In major cases, such as homicide, all prints should be photographed before lifting.

Loop

Loops have one delta (red circle). Loop ridges enter from either side of the finger, re-curve, and pass back along the side from which they entered. Loops are identified by the direction the loop opens to. Nearly 2/3 (65%) of all prints are loops. There are two different loop patterns. Radial Loop:The radial loop is named after the radius, a bone of the forearm, which joins the hand on the thumb side. To be classified as a radial loop, the loop must open towards the thumb and radius. The radial loop on a finger on the left hand will open in the opposite direction of a radial loop on a finger of the right hand. Ulnar Loop: The ulnar loop is named after the ulna, a bone of the forearm, which joins the hand on the little finger side. To be classified as an ulnar loop, the loop must open towards the little finger and ulna. The ulnar loop on a finger on the left hand will open in the opposite direction of an ulnar loop on a finger of the right hand.

Machine Guns

Machine guns are fully automatic weapons that obtain their ammunition from magazines or belts. They must have a fixed mounting to be safely fired.

Whorl

Many circular ridges are common in whorls. They make up about 30% of fingerprints. There are four different whorl patterns: Plain Whorl:A plain whorl is located between two deltas of the whorl pattern and has a minimum of one ridge that is continuous around the pattern. It looks somewhat like a pond after a pebble has been dropped into it. Central Pocket Loop Whorl:A central pocket loop whorl is not located between two deltas of the whorl pattern and has a minimum of one ridge that is continuous around the pattern. It looks somewhat like a loop print with a small whorl in the middle. Double Pocket Loop Whorl:A double pocket loop whorl is made up of two loops that swirl around each other and open in opposite directions. Accidental Whorl:An accidental whorl is a pattern that combines two or more patterns, excluding the plain arch, and/or does not clearly meet the criteria for any of the other patterns.

Class characteristics

Most forensic scientists concentrate on the physical characteristics of glass. Some common properties are: Size, shape, dimensions, thickness Color Density Refractive index Of these, refractive index is the most discriminating.

Ninhydrin spraying

Most popular method Used for developing prints on porous surfaces (paper, cardboard, raw wood) Reacts with amino acids to form a colored compound known as Ruhemann's Purple Amino acids of the print must be absorbed into the porous items for ninhydrin to work; usually takes 24 hours Prints are not permanent but will remain for several months; either photograph or scan Ninhydrin can be purchased in a spray aerosol can, a pump spray, mixed crystals, or a premixed solution for submerging evidence

Natural fiber

Natural fibers come from animals, plants, or minerals. Some common natural fibers and their origins include: •Cotton (pictured) -cotton plant •Wool-sheep •Linen-flax plant •Silk-silkworm •Asbestos-asbestos mineral •Cashmere-goat •Mohair-rabbit

Non-requested Exemplars

Non-requested exemplars are likely to be representative of the writer's true handwriting. However, these exemplars can be tricky because: The writer may not be clearly identified, so the exemplar itself will be of questionable authorship The exemplar may not be at all similar to the questioned document The exemplar needs to be about the same age as the questioned document

Shotgun Shots

Normally, distance-of-fire determinations of shotgun patterns involve comparing the size of the pattern of test fire and unknown shots. The nature of shot can make distance determinations difficult due to the distortion of the shot pattern by the shot missing the target and/or the presence of intermediate targets.

Second type of fingerprint comparison

Now let's look at the second type of fingerprint comparison when only partial fingerprints are available (referred to as developed prints), as for example at a crime scene. They can be matched to a set of known prints (referred to as inked prints) but only when enough ridges are available for a comparison. To do so, the Latent Print Examiner (LPE) uses analysis, comparison, evaluation, and verification, known as the ACE-V method, to identify fingerprints and areas of friction ridge skin.

Altercations (Obliterations)

Obliterations include a range of techniques including crossing out, writing over, or even burning the original document. Writing that has been covered with another writing instrument might be recovered using solvents or IR or UV light. In the case of burned documents, some inks or pencil leads burn more slowly than the paper and writing might be recovered by viewing the document under strong oblique light. In other cases where the document might be completely destroyed or missing, but was written on top of a pad of paper, indented writing might be recovered. Though oblique light can be used to read indented writing, electrostatic detection apparatus (ESDA) is much more effective and can even recover indented writing several pages below the original.

1901

Once Galton's suggested different fingerprint patterns, the next step was the development of a fingerprint system. In 1901, Sir Edward Henry created the Henry System, a fingerprint classification system which the FBI and other law enforcement agencies in the United States still use today. He used five classifications to put a set of ten fingerprints into one of thousands of classes. The FBI later added additional classes to make searching more practical. Henry used certain characteristics of each print—one was how many whorls are present. We will learn more about this primary classification later.

Collecting paint evidence

Paint evidence may either be a chip (or flake) or a smear. Paint chips contain most or all of the layers in the paint. Because the layer structure is intact, chips provide the most information from analysis. Paint smears are more difficult because they usually just contain the top coat of paint and, when that top coat is the clearcoat, it may be difficult to see the transferred paint. Proper collection of known paint samples from an automobile includes both collecting all layers of paint and collecting the paint from the proper location. Especially in the case of an automobile, damaged areas may be contaminated with paint from other objects and paint from far-away areas of the car may prove misleading if parts of the car have been repainted or replaced. Paint smears should not be removed from the surface of the object. Instead, the entire object or car part should be sent to the laboratory. Fallen paint chips are easily collected but investigators must not use adhesive like tape to try and keep the chips contained as this might interfere with testing on the chip.

Paint evidence

Paints contain polymers, just like fibers, except, in paints, the polymers form into sheets when they dry. Paint chemistry is very complicated and diverse. This variation can be beneficial to forensic chemists because analysis and comparison may lead to a high degree of association between known and unknown paint samples. Types of paint: automotive, structural, and artistic

Type of fingerprints...

Patent and plastic prints are generally easy to discover but latent fingerprints need to be made visible. Locating/detection and developing/visualization of fingerprints can be done in one step or in two separate steps. -Patent fingerprint, plastic fingerprint, and latent fingerprint

TOXICOLOGY

Pharmacology involves the administration of drugs, absorption into the body, actions and interactions, metabolism, and elimination. Toxicology is a branch of pharmacology that studies the harmful effects of drugs and poisons on living things. It includes the study of symptoms, mechanisms, treatment, and detection of these drugs and poisons. When the use of drugs and poisons results in death under suspicious circumstances, it becomes forensic toxicology. Much of what forensic toxicologists do is to measure the concentrations of drugs and poisons in various fluids and substances, such as blood, urine, and breath from both living persons (most usually in drunk driving cases) and dead persons (in the case of suspected overdose or poisoning).

Pistols/handgun

Pistols or handguns are divided into two subcategories: •Revolvers that contain revolving cylinders with chambers that hold individual live rounds •Self-loading pistols are usually loaded with a magazine

Long range shots

Remember that it is rare for gunshot residue to travel further that 18 inches from the barrel of the firearm. Distance wounds, by definition, would occur outside that range. Distance wounds are too far away to deposit gunshot residue. Another feature is that they typically produce roughly round wounds when the bullet passes through.

Shotgun ammunition

Remember that shotgun ammo is quite different. Instead of bullets, shotgun shells are plastic cartridge cases that contain shot (small, usually round pellets), along with a wad, propellant, and primer. Shotguns can also carry other kinds of ammunition, such as single slugs. Also remember that shotguns are not rifled. This means that rifling toolmarks, such as lands, grooves, and their striations are not present on fired shotgun ammunition.

Paper examinations

Remember that the practice of the questioned document examiner encompasses a range of fields. Along with analysis of handwriting, examiners are also called upon to examine paper and inks in questioned documents. Paper examination can be of particular use in the pages added to a printed document, where there may be no obvious differences between the print but there may be differences in the type of paper used. There are chemical tests that can be done to identify special additives on some paper but these are normally destructive and cannot be used on questioned documents. Nondestructive physical examinations include measuring the paper's size and thickness. Making a physical match of a questioned document on torn paper may also be possible.

Printed Documents

Remember that, on the whole, printed and photocopied documents seldom show any signs of individuality. In these cases, questioned document examiners might turn to other means to identify forgeries.

Requested Examplars

Requested exemplars are taken directly from the suspect, so there is no question of authenticity and admissibility in court is not usually an issue. Importantly, requested exemplars must be arranged so that the conditions are as similar to those of the questioned specimen as possible. Questioned document examiners need to bear these practices in mind: Comfort of the writer Type and color of the writing instrument Type of paper Dictating the exemplar and sprinkling in some sentences and phrases from the questioned document Taking a sufficient number of exemplars Context of the exemplar Though these and other best practices are intended to minimize the disadvantages of requested documents, the conditions of the request may still give rise to some intended or unintended alterations in handwriting. Because of these issues, many questioned document examiners prefer a combination of requested and non-requested exemplars.

Rifles

Rifles are similar to pistols but are made to be held with two hands. There are a large number of different types.

Semi-synthethic

Semi-synthetic fibers are are made from naturally occurring substances that are not fibers. Rayon (pictured), made from wood pulp, is a common fiber of this type.

Chemical properties of a plant:

Several chemical properties can be used to analyze paints. Some of the methods used target the binders present in paint while others target the pigments. Still others analyze the paint sample as a whole. --Solubility: Binders in automobile paints may differ based on the manufacturer or the cost of the car. Different binders may be insoluble, soluble, or partially soluble. --Chromatography: Paints must be chromatographed using PyGC. The resulting pyrogram will be a composite of all of the binders present in the paints. Generally, pigments do not appear in pyrolysis if they are inorganic. Infrared Microspectrophotometry: Infrared spectra may be obtained either by grounding up the entire paint chip, mixing it with potassium bromide, and pressing it into a pellet, or by making peels and running the transmission spectrum of each layer. The pellet method is useful for comparing one paint with another. The second method is useful in determining the nature of a single binder. --A cross-section of a paint chip can also be made and each layer analyzed under a microscope attached to an FTIR. --Pigments: Pigments can be analyzed using scanning electron microscopy (SEM/EDX). This quick and non-destructive method is a good complement to color analysis. Paint smears can be difficult if they fuse to the paint on the surface of the object they are transferred to. In these cases, analysis with SEM/EDX may be the best method to analyze them. If the smear can be separated, visible microspectrophotometry may be used to determine pigment color. Last, if sufficient binder is present, FTIR and PyGC may be used.

Shotguns

Shotguns differ from the other four types in that they do not fire bullets. Instead, they fire a range of ammunition such as shotgun shells or single slugs. Importantly, these guns are not rifled.

Replaced ten-pint card with computer images of fingerprints

Since the 1990's, many law enforcement agencies have replaced the inked ten-pint card with computer images of fingerprints. Life Scan captures a friction ridge image and stores it digitally in a computer database.

Soil

Soil is made up of crushed rocks and minerals mixed with decayed plant and animal material (called humus). Soil can range from almost all crushed rock (beach sand) to almost all humus (peat bog). The makeup of soil can also vary greatly, even within short distances. Because of the great skill it takes to identify soil components, the lack of a forensic classification scheme for soils, and the fact that soil is almost always class evidence, most forensic scientists only really look at soil when a shoe print or tire track has been left.

Forgeries

Some of the telltale signs of forgery include differences in line thickness and smoothness, connecting strokes, pen lifts, starts and stops, and retouching. In the case of a tracing, where a forger traces the handwriting of another person to simulate their handwriting, the quality is usually poor with an uneven and drawn quality.

Borosilicate Glass

Sometimes known as Pyrex®, borosilicate glass does not break easily when its temperature is rapidly increased or decreased, making it ideal for applications such as cookware. It is made by doping molten glass with boron.

Sub-machine guns

Submachine guns are like machine guns but are meant to be hand-held

Some pharmacology concepts (Synergism and Tolerance)

Synergism Synergism occurs when a person exhibits the magnified effects of drugs taken in combination. Take the case of an overdose where the victim ingested both barbiturates and alcohol. Though he may not have taken enough of either to cause his death, the effect of both drugs depressing the central nervous system slows the breathing until it stops and he dies. Toxicologist and pathologists must be careful in assessing the role of drugs in a death; synergism must be ruled out before drug levels are dismissed as causing the death. Tolerance Tolerance often occurs in people who continually abuse the same drug. Increasing doses of the drug are required to maintain the same effect as the original dose. When large amounts of a drug are found in a victim, toxicologists must investigate the victim's drug abuse history before making any conclusions about the role the drugs may have played in the death.

Synthetic fiber

Synthetic fibers are manufactured from materials that are not fibers. Some common synthetic fibers are: •Nylon •Polyester •Olefin •Acetate •Acrylic •Spandex •Fiberglass (pictured)

Tempered Glass

Tempered glass is used in automobile windows and plate glass windows in stores. It is specially treated so that it is up to four times stronger than regular float glass. When it does break, it forms small spheres with no sharp edges.

Widmark curve

The Widmark curve illustrates the blood alcohol level over time. There are two curves: the higher one represents the consumption of alcohol on an empty stomach and the lower one represents the consumption of the same amount of alcohol where the subject has eaten a plate of French fries before drinking. There are 5 distinct regions on the curve. In region A, within the first hour, only absorption takes place, in region B, at about the one-hour mark, elimination begins but absorption remains dominant. In region C, between the first and second hour, both processes are taking place equally. In Region D, between the second and third hour, elimination begins to dominate and, finally, in region E, between the third and fourth hour, only elimination takes place at a constant rate.

Direction of force

The conchoidal lines (curved pattern stress lines) resulting from impact and breakage can help you to determine the direction of force on the glass. Using a magnifying glass can reveal these lines in examination. As you read in the textbook, the 3R rule states that: When looking at a radial fracture line, there is a right angle on the reverse side of the impact force. The opposite is true when examining a concentric fracture: the right angle is on the same side as the direction of force. Remember that conchoidal lines are stress lines that form when certain types of materials (like glass) break. These are different from the radial and concentric fracture lines. However, knowing the type of fracture line and using the 3R rule stated above can help you to determine direction of force, which can in turn help you to make sense of evidence in an investigation.

1792 BC

The earliest reference for the use of fingerprints for identification purposes dates back to Babylon in 1792-1750 BC.

Analysis: Level 1

The first stage of the ACE-V method is the analysis. The analysis is done in three levels of details in an examined print. During the first level of detail, the examiner observes the developed print without magnification and decides on the pattern type: arch, whorl, or loop. This level of detail may narrow the number of possible donors, but may not be the source for identification.

1903

The first systematic use of fingerprints for the identification of criminals in the United States was carried out by the New York State Prison System.

Verification

The fourth stage of the ACE-V method is verification. Verification is part of the scientific process, meaning any kind of scientific work must be repeatable. At this stage another examiner independently compares the developed and inked print to either verify the result of the first LPE or to come to a different conclusion. This will reduce the number of erroneous identifications and defeat the danger of self-verification. Note: If the LPE and Verification LPE cannot reach an agreement, they would rather conclude the comparison as inconclusive, anticipating the far-reaching consequences that a positive identification or a non-identification can have such as sending innocent people to jail or letting guilty people walk free

Oblique lighting, reflective light,

The key to locating fingerprints at crime scenes is examining the scene from the suspect's perspective, asking questions such as where is the point of entry and exit, what might have been touched? When locating latent prints, the oblique lighting technique is very useful though might not work for all latent prints. Hold a light source, such as a flashlight, at a low angle and sweep the beam across the surface or object of interest. The angle of the light will allow the prints to 'pop' from the surface illuminated for you to see. Reflective light can be used as well. The Reflected Ultraviolet Imaging System uses a UV light "gun" that takes advantage of the fact that fingerprint residues reflect UV light differently than the surrounding surface. We have learned about this fact in the first week. Those lighting techniques only help to locate the print; it still has to be developed using dusting or fuming techniques.

Refractive Index

The magnitude of the decrease in the velocity of light as it passes through a transparent medium is called the refractive index (RI). The ratio is expressed as: RI=\frac{The\: velocity\: of\: light\: in\: a\: vacuum}{The\: velocity\: of\: light\: in\: the\: transparent\: medium\: of\: interest} Refraction has several properties that can be exploited when analyzing glass evidence. If two transparent materials, such as a liquid and a piece of glass, have the same refractive index, light beams that pass through them will be refracted the same amount and the materials will look like one If a transparent solid is immersed in a transparent liquid of a different refractive index, a bright halo of light will be seen around the solid. This is called the Becke Line; it disappears when the solid and liquid reach the same refractive index (Figure 22.12). If the Becke Line moves towards the glass, it means the glass has a higher RI than the liquid (Figure 22.13, left). If the Becke line moves toward the liquid, it means the liquid has a higher RI than the glass. This is used to measure the refractive index in unknown glass (Figure 22.13, right). See the example below how this can be used. Because of these properties, in particular, forensic scientists can use a hot-stage microscope when trying to determine an unknown refractive index of a piece of glass. By immersing the glass in a liquid with a known refractive index, heating the stage until the liquid's RI matches the solid's and the Becke line disappears, forensic scientists can calculate the refractive index of the glass. Let's look at an example: You immerse a piece of glass in a liquid that at 20°C has an RI of 1.6. You can see the Becke Line, but it disappears when you heat up the liquid to 45°C. You know that for this specific liquid the RI decreases by 0.01 per one degree Celsius. It took 25°C for the Becke Line to disappear. Multiply this by 0.01 and then subtract it from the RI at 20°C, which was 1.6; the RI for the glass is 1.35. Though this is a useful measurement that can be used to distinguish one piece of glass from another, remember that refractive index does not individualize glass.

Value of fingerprints

The major goal of criminal and civil investigation process is to identify people. For that, fingerprinting is widely used because all individuals have a unique set of fingerprints, even identical twins.

Physical properties of paint

The most important physical property of paint evidence is the color layer sequence. Both automotive paints and some structural paints have layers and, in the case of automotive paints, each layer may have a different composition and color. Given what you know about color layer sequence analysis, see what you can do with the paint chip samples that came into the FIVS Lab.

Adding one to the numerator

The reason why we add a one to the numerator and denominator is to avoid dealing with zeros in case that a print set has no whorls present. 25% of all people have a 1/1 primary classification, meaning their prints have no whorls.

Rifling

The rifling process bores the inside of a gun barrel from one end to the other, creating a series of lands (high points) and grooves. This produces a spin on the bullet as it emerges from the barrel. The number of lands and grooves, the direction of their twist through the barrel and the angle of their twist are all class characteristics that can help identify the manufacturer and model of a weapon.

Comparison

The second stage of the ACE-V method is the comparison in which the examiner observes the developed print and the inked print side by side and examines identified areas of similarity for corresponding features and for features that do not appear in the developed print. The examiner starts with the comparison of level 1 details (pattern) and moving on to level 2 details (minutiae). Note: There is no standard on how many of the same characteristics an examiner must find in a known (inked) and unknown (developed) print to declare if they belong to the same person or not. It is up to the examiner to decide. The general rule is the more the better. To give you an idea, previous standards varied from 10 to 16. Generally, comparisons are not made with less than 10 characteristics that need to be the same in both prints that are being compared.

Sizing

The size of rifled firearms is described in terms of bore diameter or caliber. Bore diameter is found by measuring the distance from opposing lands inside the barrel. If there are an odd number of lands, the bore diameter is the diameter of a circle that touches the tops of the lands. Caliber describes the size of a particular cartridge case or the base of a fire bullet. In the U.S., this diameter is measured in hundredths or thousandths of an inch. The diameter of a shotgun barrel is called its gauge. Gauge is the measure of the number of pellets weighing one pound that would have the same diameter as the barrel, if they were grouped in a circle.

Analysis: Level 3

The third level of detail of the analysis stage is microscopic and the examiner uses magnification to observe individual ridges of the developed print, focusing upon the location of pores and the thickness and thinness of ridges

Silver Nitrate

There are different chemical methods to develop (visualize) fingerprints. One process uses Silver Nitrate for developing prints on porous surfaces (paper, wood) but it is corrosive with metals. The chemical reacts with ions in the sweat residue, similar to the process in photographic film development. When exposed to light the substrate begins to darken. The process is decreasing in popularity due to its lower success rate and the need for constant monitoring of the development process. Below are three more common methods. Iodine fuming Ninhydrin spraying Cyanoacrylate Ester (CA) fuming

Types of glass

There are more than 700 types of glass. About 70 are in common use. Your readings discussed 5. 1)Float (glass pic) 2) Tinted (church tinted window thing pic) 3) Borosilicate (science--measuring cup pic) 4)Leaded (wine glass pic) 5)Tempered (car pic)

basic rules questioned document examiners should keep in mind....

There are several basic rules that questioned document examiners should keep in mind: No two people have identical handwriting There is a natural variation in a person's writing There is no single writing characteristic that will individualize handwriting by itself There is no set number of characteristics that must be present for an examiner to identify the author of a questioned document Handwriting contains both class and individual characteristics. Conclusions about authenticity and authorship must be based on individual characteristics.

Altercations (Erasures)

There are several different types of alterations that can be made to a questioned document. Your readings discussed 3 types. Chemical erasure on laboratory report viewed in UltraViolet light 1.) Erasures are alterations that remove original writing from a questioned document. Mechanical erasures involve rubbing an abrasive over the original writing. Though mechanical erasures very effectively remove the writing, the presence of the erasure can often be identified because the process disturbs the fibers of the paper, which can be viewed with a stereomicroscope. Chemical erasures, on the other hand, use some kind of bleaching agent to remove the dye from the ink and make it invisible. However, this type of erasure usually leaves the paper discolored and can often be identified when the document is exposed to UV (ultraviolet) or IR (infrared) light.

Fiber analysis: Chemical Analysis ( 2 ways)

There are two major methods used to analyze the chemical composition of fibers: Fourier transform infrared spectrophotometry (FTIR): This non-destructive method can determine what broad class, and the subclass a fiber belongs to. Pyrolysis gas chromatography (PyGC): PyGC is destructive; however, a pyrogram can be generated from as little as 1/8 inch of fiber. It is more sensitive than FTIR, making it better suited to differentiate between very similar fibers. Dyes can also be extracted using organic solvents and then, known and unknown dyes can be compared using thin layer chromatography or liquid chromatography.

Type of fibers

There are two major types of fibers: natural and synthetic. Some people also designate semi-synthetic as a separate type.

ten print card

This card has three rows of prints. The first row has five boxes for the fingers of the right hand, the second row has five boxes for the fingers of the left hand. Those prints are taken by rolling each finger from cuticle to cuticle. In addition, the third row includes four tap print boxes, one for the four fingers of each hand together and each thumb. Those prints are tapped into the proper box.

Tinted Glass

This type of glass contains colorants from various colored minerals. It is often used in decoration and, sometimes, to reduce glare or heat penetration.

Float Glass

This type of glass is used to make windows and other flat glass objects. Another important property of float glass is that one side of it will fluoresce in ultraviolet (UV) light

What two factors does writing depend on? (forensic science and writing)

Though handwriting is often taught the same way to many people, over time, the writing process is internalized and every person begins to add their own embellishments. However, handwriting is not static; it changes over time in response to age, writing purpose, health, and drug use. Handwriting comparison depends on two factors: the presence of sufficient unique characteristics in the questioned writing, and the proper collection of exemplars.

Serial Number Stamps

Though serial numbers can be filed away, the stamping process strains the metal beneath where the actual numbers appear and that strained metal retains an imprint. Firearms examiners can use a solution to dissolve the metal and reveal the lost serial number. One popular solution uses hydrochloric acid, water, and cupric chloride. After the solution has been applied to the metal and the serial numbers reappears, the numbers will fade again and be lost. Examiners must be ready to record and photograph the serial numbers before they begin the restoration process.

Altercations (Through writing additional..)

Though the writing in an addition to a questioned document is often too minimal to identify an author, the additions themselves are often easily identified when the chemical characteristics of the ink in the pens are different. When exposed to UV or IR light, the addition made with the new pen may show up in another color.

Screwdrivers, Wirecutters, and Other Metal Tools

Though your readings didn't spend much time on them, it is important to note that other tools can leave important clues. Similar to the different toolmarks in firearms, tools like wirecutters and screwdrivers can leave striations as they scrape or otherwise impress themselves on other pieces of metal. The known and the unknown stria can be compared for a match. Note that, though you should be able to individualize toolmarks in general, a forensic scientist must take care in extending the observations about firearms and cartridges to all tools.

Photographing tire treads

Tire impressions must be documented with photographs or casting before weather conditions, such as rain, destroy them. Dental stone is also the preferred material for casts. In snow, casting wax is used. Casting is always more detailed for footprint impressions but might not be as useful in tire marks. The casts are big and bulky and steep inclines can hinder an even application of the dental stone. In general, detailed high-resolution photographs might be a better way of documenting tire tread impressions.

Fracture Lines

Two different types of fracture lines are usually present near the point of impact. Identifying these fracture types can help you to sequence fractures when two or more are present. Radial Fractures Radial fractures extend outward in a line from the point of impact, breaking first on the opposite side of the force. Remember that no radial fracture can extend through an existing fracture line. Concentric Fractures Concentric fractures make relatively circular patterns around the point of impact, breaking first on the same side as the force.

FIBER MORPHOLOGY (characteristics and properties that help you identify fibers)

Type: This is the most important characteristic. Tests to classify the fiber origins include microscopy, burn testing, solubility testing, and chemical treatment to determine affinity for dye. Remember that some of these methods are destructive to the evidence and should be the last method of testing performed on the fiber in question. Size: Natural fibers are sized either using their diameter, measured in micrometers (microns). Synthetic fibers are usually measured in denier, the weight of a bundle of fibers 9,000 meters long. Cross-section: The cross-section of a fiber may give a clue to its end use. Color: Color can be examined with the eye, but to guard against issues of subjectivity and the lack of qualitative data, a microspectrophotometer should be used to obtain the visible spectrum of the fiber. Crimp: Some fibers, like the cotton you viewed previously, have a natural wave, called a crimp, while synthetic fibers have to have a crimp applied.

Can you individualize a single fiber to a particular fiber source? (picture of dark image with one small fiber)

Typical fiber evidence of individual fibers or small groups of fibers do not have enough unique characteristics to individualize them to a particular source.

Fiber analysis: Microscopy

Using a microscope, forensic scientists can view general characteristics of fibers, including: Cross-section of trolobal synthetic fibers Source: FBI.gov Cross-sectional shape: As mentioned previously, analyzing the cross-sectional shape of a fiber can give clues as to its end-use. Diameter: The diameter of a fiber is measured differently, depending on its shape. Delusterants: Synthetic fibers are often treated with delusterants to reduce their inherent shininess. By analyzing the shapes, sizes, and distribution of delusterants in known and unknown fibers, the forensic scientist can determine the degree of association between them. Refractive index: Like glass, fibers have a refractive index. However, the shape of a fiber may cause it to have more than one refractive index. Color: As mentioned previously, though the eye can detect color on its own, microspectrophotometry is used in order to objectively determine the color of a fiber.

minutiae, or Galton's details.

Within the pattern area of the fingerprint are certain ridge characteristics --Dot: are tiny round ridges -- Short Ridge:are small isolated segments of a ridge --Enclosure/Island:is a ridge that forms a fork, then a complete circle, and then becomes a single ridge again. They are also called islands --Ending Ridge:is a simple straight ridge whose end is not connected to other ridges. --Bifurcation: are ridges that split into two ridges like a fork. --Trifurcation: are ridges that split into three ridges.

fluorescent powders

You can also use fluorescent powders, available in various colors and especially effective on multicolored surfaces that would be problematic for other types of powders. Application with a feather brush is recommended, as very little powder is necessary for print development. Prints developed with fluorescent powders must be examined with forensic or UV light sources. There are also magnetic powders that are applied with magnetic brushes. The brush is moved across the surface without touching it; the powder clings to the surface of the fingerprint residue but not the cracks in the surface. Note: Never apply too much powder or too much pressure.

DELTA'S AND TYPE OF FINGERPRINT

ZERO DELTA = ARCH ONE DELTA = LOOP TWO DELTAS = WHORL

fingerprints can arise from...

dermal papillae, the layer of cells between outer skin (epidermis) and inner skin (dermis).

Automated Fingerprint Identification Systems (AFIS)

have become more useful with computers having larger memory capacity for automated search processes of fingerprints. They operate by anchoring the position of a fingerprint and searching databases using two types of ridge details (minutiae): Bifurcations Ridge endings Unlike in the movies, AFIS rarely matches fingerprints to one individual. Usually it is a list of matches that the fingerprint examiner then analyzes and compares. In 1999, the FBI implemented a new, entirely digital system, called the Integrated Automated Fingerprint Identification Systems (IAFIS) that compares a person's set of ten fingerprints against a database of millions of prints in a few minutes.

Powdering

is one of the most commonly used means for developing latent prints. It is cost effective, easy to use, and yields high quality. Powder adheres to the water and oils in the latent print but can also adhere to any other water-based substance on the substrate. Note: If other moisture is on the surface, do not use powder, as this will most likely destroy the print and possibly the powdering brush as well. There is a large variety of fingerprint powders in different colors that are applied with camel hair or nylon brushes.

Impression

is when one object makes physical contact with another leaving some of its physical characteristics on the recipient. Soft or pliable materials such as putty, mud, concrete, and soft dirt leave three dimensional impressions (showing length, width, and depth). Hard surfaces such as dirt, dust, blood, ink have two dimensional impressions (showing length and depth).