CJE2600
Criminal Investigation
Chapter 4
Physical Evidence
Dr. E. C. Buchholz
LEARNING OBJECTIVES
1. Distinguish between class and individual characteristics.
2. Contrast known and questioned sources.
3. Describe the basics of taking soil samples.
4. Discuss importance of taking shoe impression using Dental Stone.
5. Summarize the proper way to collect loose paint chips at a crime scene.
6. Differentiate between radial and concentric fractures.
7. Explain minutiae.
8. Describe how plastic prints are formed.
9. Describe dusting for latent prints using traditional powder.
10. Explain what information can be obtained from examining hair.
11. Discuss methods of collecting and storing fibers, cloth fragments, and impressions.
12. Understand how to locate, identify, and use tools to obtain fingerprints.
13. Identify five circumstances in which forensic odontology can be an asset.
14. Discuss how to locate and collect blood.
15. Identify the determinations that can be made from firearm evidence.
16. Define questioned document.
CLASS AND INDIVIDUAL CHARACTERISTIC EVIDENCE
• Class: a group of objects or persons with characteristic physical evidence common to it
Examples include soil and hair
Should not dismiss as it may show individual characteristics through lab exam
• Individual characteristics can be identified as having originated with a particular person
or source
Establishes individuality
Examples include fingerprints and footprints
CLASS AND INDIVIDUAL CHARACTERISTIC EVIDENCE
• Pattern Evidence
• Physical evidence which produces familiar patterns with regularity
• Generally created by the contact of two surfaces (persons, vehicles, or objects) that
results in the formation of compression, imprints, or markings
• May be a transfer of material from one surface to another resulting in pattern evidence in
the form of a stain or a deposit
• Pattern Evidence (continued)
• May result from the fracture, breaking, or cutting of an object
Bloodstain
Glass fracture
Burns
Tire and skid mark patterns
Projectile trajectory patterns
Injury wound pattern
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Unknown and Questioned Samples
• Recovered crime scene sample whose source is in question
Whose fingerprints are on the window used as a point of entry?
• Questioned evidence that may have been transferred to an offender during the
commission of a crime and been taken away by him or her
Do any of the hairs combed from the suspect’s hair match those of the victim?
• Evidence from an unknown or questioned source that can be used to link multiple
offenses
Was this gun used in a double homicide a week ago?
Known Samples
• Standard or reference sample
Material from a known or verifiable source
Blood a suspect to compare to blood on the victim’s clothing
• Control or blank sample
Material from a known source that was uncontaminated by the crime
Carpet fibers
• Elimination sample
Taken from a source known to have had lawful access to the crime scene
Police officer(s)
Medical technician(s)
Occupant(s)
SOIL EVIDENCE
• Soil evidence is important when the suspect drives/walks on unpaved areas
• It is picked up by:
tire treads
shoe bottoms
pants cuffs
• It may also be located in:
subject's vehicle
articles in a suspect's trunk
SOIL EVIDENCE
• Soil samples can provide important evidence in criminal investigations.
• The soil can be analyzed using microscopes, x-ray diffraction and DNA sequencing to
provide detailed information on the soil composition.
• This information can be compared to a soil type database and matched to a geographical
location.
• This evidence can be used to trace the movements of the victim and suspects in relation
to the crime.
• Avoid cross contamination of the samples when packaging soil
Pollen evidence
• Pollen in soil or on plants and grass can help an investigator determine whether or not a
suspect was at a scene.
• Pollen can help to determine whether death occurred at the location where a body was
found or whether a body has been moved to that location.
• Pollen deposited in the nose can also indicate whether a victim was alive when deposited
at a location and can help by determining the season of death.
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Cadaver Decomposition in Soils
• Taphonomy is the study of the processes that affect the decomposition, dispersal, erosion,
burial, and re-exposure of organisms after, at, and even before death.
• In forensics, taphonomy aims to provide evidence for the courts in cases where cadavers
have become decomposed over time by providing an approximate post-mortem interval
(PMI).
FOOTWEAR AND TIRE PRINTS AND IMPRESSIONS
• Footwear prints and impressions should be photographed:
As part of the general scene
Photographed with a scale
• Dental Stone is used in casting impressions
Prints
• Footwear, such as boots, shoes, and sandals
• The soles of feet
• Tires
• Residue Prints
Formed when soles of footwear, soles of feet, and tires are contaminated with foreign matter
such as blood or dust and leave a print on a firm base
Floor, seat of a chair, paper, cloth
• Impressions
Result from footwear, feet, and tires treading in some moldable material, such as earth, clay,
and snow
FOOTWEAR IMPRESSIONS
• Photographs of footwear impressions at a crime scene
Take general crime scene photos showing the location of the footwear prints.
Take photos from directly overhead using lighting and a tripod.
Include a linear scale next to, and on the same plane as, the footwear prints.
Place a label in the area being photographed to correlate photos with crime scene and photo
log records.
FOOTWEAR IMPRESSIONS
Software Programs
• SICAR compares footwear and tire evidence
• SoleMate contains the records of 24,000 sports, work, and casual footwear
• CrimeShoe has a collection of 23,000 shoe and sole images representing 950 brands
• TreadMate is a reference collection of 8,500 tires
Residue Prints
• Two dimensional: length and width
• May be from a dry origin or a wet one
Dust
Oil
Blood
• May or may not be readily visible
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Impressions
• Three-dimensional
Length, width, and height
• Physically preserved by casting
• Dental stone or die stone
Paint
FBI National Automotive Paint File (NAPF)
Housed in the Chemistry Unit, NAPF has entries from as far back as the 1930s.
The reference collection of automotive paint-color panels can be searched by make, model, and
year (MMY) to assist in identifying vehicles involved in crimes. These color panels represent
vehicles manufactured for sale in North America. Each year, automotive manufacturers send
newly introduced colors to the FBI Laboratory via a color-standard panel.
The Paint Data Query (PDQ) is a second database used in MMY searches. Unlike the NAPF
database, the PDQ uses the layer structure (number of layers, color of each layer, and order in
which they are applied) and the chemical composition of the individual layers of paint on a
factory-applied automotive finish. The Royal Canadian Mounted Police (RCMP) maintains the
PDQ and has expanded the database to include Japan and the European Union.
Paint as Evidence
• Paint as evidence falls into two main categories
• Paint can simply indicate the class from which it comes, such as differentiating
automobile paint, house paint, nail polish and other types of paint.
• This is usually done through very detailed chemical analysis of the various layers of paint
and physical examination of paint samples.
• Although various manufacturers may use the same supplier of paint the layers and colors
may vary from manufacturer to manufacturer.
Paint as Evidence (continued)
• Paint can also indicate individual characteristics.
• This is only possible when there is an exact match of the edges of two paint chips.
• When the physical properties such as the color and number of layers and the chemical
and biological profiles show multiple points of similarity with reference sample the
probability of a common source increases.
Glass as Evidence
• Glass is found in many types of cases.
• Glass, like paint, is often involved in burglaries and hit-and-runs.
• Glass fragments easily embed in shoes, clothing and hair of people involved in the
breakage of glass.
• Glass can give both class characteristics and, in the case of a reconstructed piece of glass
that was broken, it can provide individual characteristics when the fractured pieces fit to
either.
Glass
• Radial Fracture
Move away from the point of impact
• Concentric Fracture
The lines more or less circle the same point.
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Glass (continued)
• Lab examination of glass evidence may determine:
Type of glass—tempered or container
The direction of force used to break the glass
The direction and sequence of shots fired through a closed glass window
Similarity between evidence glass and standards
A fracture physical match, establishing the pieces were formerly joined
COLLECTING GLASS AND PAINT EVIDENCE
• Paint may be collected from the suspect's tools or clothing.
• Paint can often be collected in dried chips.
• Use a clear solid plastic container (ideal) or paper envelopes (acceptable) to package—do
not use tape, plastic bags or cotton.
COLLECTING GLASS AND PAINT EVIDENCE
• Glass is a common form of evidence at burglary scenes.
• Photography should precede the collection of glass evidence.
• Precautions to be taken:
Glass evidence from combing hair should be done over clean paper
Clothing and shoes should be packaged separately, and never commingle victim’s and
suspect’s items
Air dry wet clothing
Medical personnel should be used to recover glass embedded in the skin and open wounds of
victims and suspects
Laminated glass, such as windshields, should be labeled “inside” and “outside”
Use a separate vacuum bag to collect glass from different areas
FIBERS, CLOTH FRAGMENTS, & IMPRESSIONS
• Fibers are of value as evidence because they have such variables as material type, number
of fibers per strand, number of strands, thickness of fibers and strands, amount and
direction of twists, dye content, type of weave, and possible presence of foreign matter
embedded within them
• Fibers may be located on the body of the victim and/or the suspect.
• Cloth fragments may be found at the scene of a violent crime.
• Cloth fragments may also be
found at the suspect's point of approach or exit.
String, Cord, Rope, & Tape
• Commonly found in robbery, murder, rape, and kidnapping cases
• Also, accidental hangings by children and sexual asphyxiations
• Same characteristics of fibers
Composition, diameter, color and construction
FINGERPRINTS
• Come from palms, fingers, toes, and soles of the feet
Have ridges that can form a fingerprint
• Fingerprints are a replica of the friction ridges that touches the surface on which the print
was found
• Minutiae
Ridge characteristics
• A print of one has never been known to duplicate exactly another fingerprint
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• A person’s fingerprints do not change
• MAJOR FINGERPRINT PATTERNS
Population:
• 65% have loops
• 30% have whorls
• 5% have arches
THREE BROAD CATEGORIES OF LATENT FINGERPRINTS
• Plastic prints
Created when the fingers touch against some pliable material such as putty
• Patent/contaminated/visible prints
Formed when the fingers are contaminated with such things as oils, ink or blood and touch a
clean surface
• Latent/invisible prints
Left on a surface from the small amounts of body oil and perspiration that are normally found
on friction ridges
Made visible by “developing”—making it visible
CONDITIONS AFFECTING THE QUALITY OF LATENT FINGERPRINTS
• The surface on which the print is deposited
Non porous surfaces, which are not absorbent
Mirrors, glass, plastic, painted wood
Porous surfaces, which are absorbent
Documents, cardboard
Semiporous surfaces, which don’t fit easily into the above categories because they both
resist and absorb fingerprints, which may or may not soak into the surface
Glossy cardboard, magazine covers, cellophane
CONDITIONS AFFECTING THE QUALITY OF LATENT FINGERPRINTS (continued)
• The nature of the material contaminating the fingerprint
Powders may be quickly destroyed, while blood, ink, or oil can last longer
• Any physical or occupational defects of the person making the print
• How the object on which the prints appear was handled
Movement of the finger
• The amount of the contamination
If the finger is very contaminated, both the ridge surface and their “valleys” get filled up
Locating prints
• Always wear latex, nitrile, or other suitable gloves
• Thoroughly search all surfaces in and around the crime scene
• The fact that an offender may have worn gloves in no way lessens the need for a
complete search
• Never assume the offender took precautions against leaving prints or destroyed those left
• Use ambient lighting, a bright flashlight, and or a forensic light source (FLS)
Infrared or ultraviolet light
METHODS OF DEVELOPING LATENT PRINTS
• Traditional powders
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Most common
Various colors, depending on background
METHODS OF DEVELOPING LATENT PRINTS
• Fluorescent Powders
Chemically enhance the print when viewed under FLS or laser illumination
• Chemicals
Variety used to develop and enhance latent prints
Applied by spraying or brushing surface being examined, by fuming, or by dipping the object
in a solution
METHODS OF DEVELOPING LATENT PRINTS
• Cyanoacrylate (CA) or superglue fuming
Developed in 1978
CA is heated in a high-humidity chamber
As the fumes condense, they develop white-colored latent prints in 5 to 15 minutes
• Easy to use
• Produces remarkable results
• Low cost
METHODS OF DEVELOPING LATENT PRINTS
Portable Superglue Fuming Chamber
METHODS OF DEVELOPING LATENT PRINTS
• Visualization under:
Laser
Alternative light
Ultraviolet illumination
RUVIS (Reflected Ultraviolet Imaging System)
• Generic name for a class of lighting and imaging systems that have been increasingly
used in the past several years.
• When the UV light strikes an undetected fingerprint on most nonporous surfaces, it is
“bounced” back to the RUVIS and the image is intensified.
• Prints located in this manner can then be developed and photographed.
Locating Prints
LOCATING PRINTS
FORENSIC DENTISTRY
• Forensic odontology is a specialty that relates dental evidence to investigation
Most common involve missing persons and unidentified persons
• Analyses of bite marks has played a major role in many cases
• Teeth marks may be left in food, pencils or other items left at crime scenes
• Bite marks can help eliminate
or identify suspects
DENTAL COMPARISON
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•
Dental records are very useful in helping to identify unknown persons who have been the
victim of foul play or who have been reported simply missing.
FORENSIC DENTISTRY CONTRIBUTIONS
• Identify a found head
• Identify decomposing, burned, skeletonized body
• Sexual assault or other abuse where there are defensive or aggressive bite marks
• Mass casualties of attacks and natural/industrial disasters
• Identify a presumptive or reasonably believed identity
e.g., al-Qaeda terrorists Abu Musab al-Zarqawi and Mohammed Atef
DENTISTRY CONTRIBUTIONS
• Postmortem (after-death) dental profiling
Some idea of racial characteristics
Age at time of death estimate
Gender
Analysis of dental pulp and cranium
Social class
By presence or absence of various types of dental care
Habits
Pipe smoking
Nail biting
BITE MARKS
VICTIM
• Bites are documented using color photography
• Should be swabbed for saliva
• Cast of victim’s teeth should be taken
For comparison to any bites on suspect
Bite Marks
SUSPECT
• The suspect should not be alerted of impending warrant
May have teeth pulled, altering dentition
• Dental records
• Photographs
• Clinical exam
Maximum mouth opening
Misaligned, broken, missing teeth
• Sample bite marks in wax
National Dental Image/Information Repository
HAIR
• Both victims and suspect can transfer it to each other or the scene
• Easy to locate and recover, and durable
• Primarily associated with violent crimes
Hair Contributions
• Racial characteristics
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• Somatic (body) area origin of hair
Eyelashes, pubic, scalp, beard
• Manner in which it was removed
• Damage
Blunt force trauma, burned
• Types of drugs ingested and how recently
• Hair treatment
Bleaching, shampoo residues, dyes
• Determination whether known and questioned hair samples could have a common origin
Hair (continued)
• Nuclear DNA (nDNA)
Passed on to both parents to their offspring
If a hair has a root, or other tissue attached, establishing individual identify is possible from
nDNA
• Mitochrondrial (mtDNA)
If only a hair shaft
Is inherited only from the maternal line
It is not possible to establish individual identity because other people along the same maternal
lines share it
mtDNA can be used to exclude suspects
• Do not overlook the potential probative value of animal hair
Upon searching his house and motor home, they found several dog hairs. Westerfield didn't
own a dog, but the girl's family did. By comparing the DNA of the dog hair to that of her family
dog, forensic investigators determined it was likely the hairs matched. This evidence helped
convict David Westerfield.
Hair
• Document by photos, the evidence log, and by diagram where the hairs were recovered.
• Do not submit wet hairs to the lab; they should be allowed to air dry.
• If they are firmly attached to an object, leave the hairs intact and submit the object.
• When visible hairs are not firmly attached to an object or the object is too large to submit
to the lab, carefully remove them with clean tweezers.
• If hairs were possibly transferred to the victim’s and/or suspect’s clothing, keep their
clothes apart. Package each article of clothing separately and submit to the laboratory
separately.
• Do not overlook the potential probative value of animal hair; if a victim’s pets were
present at the time of the offense, samples should be pulled from them and handled in the
usual manner.
BLOOD
• DNA analysis can provide individual identification
• Bloodstains (blood spatter)
Produced by type, location, and number of wounds inflicted
Type of weapon involved
Movements by the victim while trying to escape, defend himself/herself, or attack offender
Changing in the location of the victim’s body owing to its being moved by the offender or
someone
Continuing postmortem violence to the body by the offender
IDENTIFYING AND ANALYZING BLOOD STAINS
• If blood at the crime scene is fresh and relatively uncontaminated, identification is not
difficult
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• If the conditions at a crime scene are otherwise it is more difficult to identify
• Hemident
Used for preliminary field test
• Luminol
A water-based spray, locates trace amounts of blood within 30 seconds, creating a blue glow
after lights are turned out
• Blood analyses is important because of the value of DNA typing
HEMIDENT
Blood Analysis
• Species
Human, dog, horse, etc.
• Gender
• Blood type and DNA profile
• Use of drugs or alcohol by blood source
• Presence of certain types of illness
Venereal disease
• Presence of carbon monoxide
• Whether the source was a smoker
SOURCES OF DNA EVIDENCE
These are common sources of blood and DNA evidence that investigators need to be aware of in
conducting crime scene searches.
Firearm Evidence
• Determination from firearms evidence lab examinations of firearm evidence may answer
the following questions
Was this bullet fired from this weapon?
What else can be learned from the bullet?
What determinations can be made from cartridge cases?
What miscellaneous determinations can be made by examination of firearms evidence?
BULLET IDENTIFICATION
• Rifling
Consists of grooves cut or formed in a spiral nature, lengthwise down the barrel of a firearm
• Caliber
Diameter of a bullet
• Bore
The diameter of the barrel’s interior between its opposing high sides, or lands
Low sides of the barrel’s interior are called grooves
• Signature
Marks left on fired bullets from manufacturer defects and the use of a firearm
• Matching striations on bullets recovered at different crime scenes can tie together
information from several cases
BULLET IDENTIFICATION
• When a bullet passes through the barrel of a weapon distinctive scratches are caused
• These scratches can be compared to bullets fired through firearms in question
• Identification is affected by the condition of the gun and of the bullets
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What else can be learned from the bullet?
• Evidence of the class characteristics of the weapon that fired it
Number of lands and grooves
Height, depth, and width
• Given make and model will have the same class characteristics
• Examination of fired bullet suggests
Type of weapon fired from
Whether bullet is a hard-nose or soft-nose projectile
The pitch and direction of twist within the barrel
If of sufficient size, through weighting and measurement, its caliber
Often recovered as fragments, thus only caliber may be implied
What else can be learned from the bullet? continued
• May be able to see fabric impressions on the bullet’s nose as the bullet passed through
victim’s outer garment
• Minute traces of blood, tissue, bone, fabric, or other materials
• Prints
May be problematic due to discharge heat and friction
What determinations can be made from cartridge cases?
Striations made on the outside of the cartridge case caused by action of the magazine or by
the slide action
Firing pin impression made on the base of the cartridge case
Marks left on the cartridge case as the exploding gases that propel the bullet forward force the
casing outward against the chamber wall and backward against the breach face of the weapon
Extractor marks made when the case is pulled out of the chamber and ejector marks made
when the case is “kicked out”
What miscellaneous determinations can be made by examination of firearms evidence?
• Does the weapon function properly, including safety features?
• Has it been modified to discharge in a manner other than designed?
• What was the shot trajectory?
• Is the trigger pull on a weapon “hair” nature, require only the slightest pressure to pull it
Accidental shooting
Obliterated serial numbers can sometimes be restored
TOOL MARKS
• Any impression, cut, gouge, or abrasion made when a tool comes into contact with
another objet
Identify the type of tool that made the mark or impression
Establish the action used to operate the tool
Specify size and other characteristics of the tool
Identify unusual features
Broken tip on a screwdriver
Establish whether two portions of a tool were ever commonly joined
Determine whether “this” tool could have made “that” impression or mark
QUESTIONED DOCUMENTS
Document
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•
Anything on which a mark, symbol, or writing is made for the purpose of transmitting a
meaning
• May not be visible to the naked eye
Questioned Document
• One whose origin or authenticity is in doubt
Checks, credit cards, etc.
COUNTERFEIT SOCIAL SECURITY CARDS
• Social security numbers are an important source of identification in America
• Criminals often try to produce social security cards in order to assume new identities
• Illegal aliens also often try to obtain fake social security cards
TECHNIQUES FOR IDENTIFYING QUESTIONED DOCUMENTS
• Handwriting and handprinting examinations
• There are three types of forgery:
Traced forgery
Simulated forgery
Freehand forgery
TECHNIQUES FOR IDENTIFYING QUESTIONED DOCUMENTS continued
• Photocopier examination
• Paper examination
• Age of documents
• Burned or charred paper
• Altered or obliterated writing
• Writing instruments
• Mechanical-impression instruments
• Typewriting
Laboratory Determinations
• Determine whether authentic or counterfeit
• Recover indented writing
• Identify the class/type of the writing instrument
Ball point pen, felt-tip pen, pencil
• Determine whether inks of know and questioned samples have consistent characteristics
IRS and Secret Service maintain the International Ink Library with more than 9,500 samples
• Decipher charred, burned, water-soaked documents
• Match ends of cut/torn paper
• Establish source of paper
• Detect erasures, obliterations, alterations
• Establish relative age of document
END OF CHAPTER 4
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