History of Hair Comparison in Forensics

Introduction to Trace Evidence

• Fiber is the smallest unit of a textile material with a length many times greater than its diameter
• Fibers occur naturally from plants and animals
• Humans have created a wide variety of stronger and cheaper fibers
• Yarns form from fibers spun together
• Fabrics are created from fibers woven or knotted together
• Fiber transfer is affected by:
  • Type and length of the fiber
  • Spinning method
  • Fabric construction
• Trace evidence is evidence in small quantities that may be difficult to see
• Examples of Trace Evidence
  • Hair
  • Fiber
  • Soil
  • Paint
  • Glass
  • Gunshot residue
  • Explosive residue
  • Fire residue

Locard’s Exchange Principle & Trace Evidence

• Locard’s Exchange Principle states that every contact leaves trace evidence
• Fiber transfer can occur between victim and offender’s clothing
• Fiber transfer can occur from the crime scene to offender's clothing and vice versa
  • Examples include carpets, bedding, chairs, and rugs
• Fiber transfer isn’t guaranteed with every contact
• Locard's Exchange Principle states that every contact leaves trace evidence between victim and offender
• Paul Kirk articulated that whatever a person touches, what they leave, consciously or unconsciously is a silent witness against them
• In addition to fingerprints and footprints, trace evidence also consists of hair, clothing fibers, broken glass, tool marks, paint scratches, blood, or semen
• Trace evidence requires a painstaking search by the forensic technician of a crime scene and body

Searching the Body

• Document any perishable trace evidence during the initial body search
• Ensure immediate protection or processing of perishable samples
• Outdoor crime scenes require special care because of bad weather, compared to indoor crime scenes.
• Utilize pop-up canopies to preserve evidence
• Examples of perishable trace include:
  • Hair or fibers that can be blown away
  • Gunshot residue that can disappear due to rain
• Ensure that any trace evidence that might move when rolling the body is noted

Detection of Trace Evidence

• Trace evidence is difficult to find due to its small size and requires meticulous searching
• Magnification is a way to help detect trace evidence
  • Magnifying glass, handheld devices are best
• Lighting is a way to help detect trace evidence
  • Flashlights should be held at an angle
  • UV lighting can cause some evidence to fluoresce
  • Alternate light sources use a range of different wavelengths

Collecting Fiber Evidence

• Photograph evidence before collection; use special lenses for close-ups
• Bring the container to the fiber to prevent accidental loss
• Technicians use forceps to collect fibers into a druggist’s fold and then an evidence bag
• Use tape to lift fibers against a white index card
• Vacuum the area as a last resort
• Collect fiber samples within the crime scene for testing
  • For example, rugs, towels, and bedding
• Always photograph the trace evidence before collection
  • Utilize special lenses to see small evidence and ensure the trace evidence should take up most of the frame
• It is vital to gather control samples of possible sources, if possible.
• The most important collection rule; bring the container to the evidence instead of the evidence to the container
• Methods to collect trace evidence include:
  • Post-it sticky note
  • Plastic forceps
  • Sticky tape
  • Evidence vacuum should only be used as a last resort

History of Textile Industry

• Experts estimate humans started wearing clothes 50,000 years ago
• 8,000 years ago, archaeological evidence indicates humans grew flax and wove textiles
• Textile refers to a fiber-based material
• 5,000 years ago, humans selectively bred sheep for wool over hair/fur
• In 1935, DuPont commercially introduced nylon after seven years of development

Types of Fibers

• Two main fiber groups exist: natural and artificial
• Natural fibers include vegetable, animal, and mineral
  • Asbestos is a mineral fiber
• Artificial fibers can be semi-synthetic and synthetic
  • Rayon is a semi-synthetic fiber
  • Nylon and polyester are synthetic fibers

Vegetable Fibers

• Vegetable fibers consist of cellulose from plants
• Seed fibers include cotton, kapok, and coir
• Stem fibers include flax, linen, jute, ramie, and hemp

Animal Fibers

• Animal fibers consist of long protein chains
• Wool is an animal fiber source
  • Obtained from sheep, goats, rabbits, camelids, llamas, and alpacas
• Silk is another animal fiber source
  • Obtained from silkworms

Wool Industry

• Wool is an animal fiber consisting of proteins and a few lipids
• Wool comes from various animals, including sheep, goats, rabbits, and camelids
  • These include camels, alpacas, llamas, vicuñas, guanacos
• Wool has been used for clothing for thousands of years
• Wool insulates against heat and ignites at higher temperatures, making it useful in high-risk fire situations
• China is the largest wool producer, followed by Australia and New Zealand

Silk Industry

• Silk is a naturally occurring fiber from silkworm larvae (caterpillar) cocoons
• Silkworms create the silk cocoon using their saliva glands
• Silkworms, originating from China, have been domesticated over thousands of years to improve silk production and quality
• The Silk Road is named after the silk produced from silkworms
• Annually, 10 billion cocoons are needed to produce 70 million pounds of silk

Mineral Fibers

• Mineral fiber is a naturally occurring fiber that comes from a mineral
• Asbestos is the only naturally occurring mineral fiber
• Archeologists discovered asbestos was used in ceramic pots in the Stone Age
• Asbestos was used until the 1970s due to its fire resistance and electrical insulation
• Asbestos is now a health hazard linked to cancer

Semi-Synthetic Fibers

• Semi-synthetic fibers consist of raw materials with naturally long-chain polymer structures that are modified and partially degraded by chemical processes
• Rayon is created from plant cellulose (wood pulp)
  • It is a versatile fiber used to “feel” like silk, cotton, or linen
• Bamboo is created from plant cellulose (bamboo plant)
  • It is popular due to its sustainability

Synthetic Fibers

• Synthetic fibers come from man-made fibers created in a lab
• Types of synthetic fibers:
  • Nylons: made from petroleum and are stronger than steel wire
  • Polyesters: commonly used in clothes and cloth, easy to wash and wrinkle-free
  • Acrylics: made from petroleum and are soft and warm, like wool

Nylon Industry

• Nylon is a synthetic thermoplastic made from petroleum
• Nylon was first commercially produced in 1935
• Nylon stockings became popular in 1940 for women
• During World War II, nylon was to make parachutes, tires, tents, ropes, ponchos
• Nylon is used for carpet, tires, ropes, threads, sleeping bags, dental floss, and seat belts

Case Study: Richard Marc Evonitz

• In 2003, 16-year-old Sofia Silva was kidnapped in VA, and her body was later found in a creek
• In 2004, two teen sisters, Kristen and Kati, were kidnapped
  • All three victims had blue and pink acrylic fibers on their bodies
• In June 2002, Kara Robinson was taken in SC
  • She escaped and led police back to the apartment of Richard Evonitz
• After a high-speed pursuit, Richard died by suicide
  • Newspaper articles about the other killings were found in his apartment
• Fibers found were consistent with a pink bathroom rug and dark blue fur found in his apartment
  • DNA from hair matched to Richard Evonitz

From Fibers to Fabrics

• Fibers can be spun to create yarn and then woven/knitted into fabrics
• Fabric examples:
  • Chiffon
  • Cotton
  • Denim
  • Lace
  • Leather, created by treating animal skin with chemicals to prevent decay
  • Linen
  • Satin

Forensic Fiber Comparison

• The most common fiber analysis equipment is a comparison microscope
  • It is possible to compare a known (rug, towel, bedding, rope) sample with an unknown sample
• Torn or ripped fiber samples can be compared to known samples by matching tear patterns
• Labs use comparison standards for ropes, twines, and tapes
  • They can be matched to the manufacturer and its uses

Case Study: Wayne Williams

• In 1981, a police officer heard a splash and stopped Wayne Williams
• Two days later, Nathan Carter was found and last seen with Williams
• Hairs and fibers from Jimmy Payne matched Williams' home, car, and dog
  • Williams was found guilty and sentenced to life in prison
• In 2007, dog hair was a mitochondrial match to the William's dog (1 in 100 chance)
  • DNA testing matched 2.5% of the population, including Wayne Williams

Locating Fiber Evidence

• Finding fiber evidence is difficult without concentrated search
• Photograph and video the area, collect hair and fibers immediately
  • Use sticky notes or tape
  • Label the bag
• Recommended search equipment:
  • Magnifying glass
  • Flashlight
  • Alternate Light Source -Ultra-Violet Light & Fluorescent Lighting

Issues with Fiber Samples

• The FBI began reviewing hair and fiber evidence in the 1990s
  • Before this, many experts testified that fibers are a "match"
• DNA started to be requested as more frequently
  • Previous convictions with fiber evidence were exonerated
• Currently, experts can testify that fiber evidence is consistent rather than an exact match unless it is torn and matches a shape
• The rarer the fiber, the greater importance the fiber can be
  • White cotton and blue denim are the common fibers

History of Hair Comparison

• Hair comparison dates back to the 1800s
• The first case to use hair evidence was Knoll v. State in 1882
  • A man was murdered in the swamp
  • The suspect had hair and blood in his wheelbarrow
  • An expert matched the hair from the victim to the wheelbarrow
  • The suspect was convicted, but the conviction was overturned on appeal
• In 1883, a forensic textbook, The Principles and Practice of Medical Jurisprudence, featured a chapter on hair analysis
• Dr. Sydney Smith used a comparison microscope for the first side-by-side analysis in 1934
  • Hair from a suspect was compared to hair from a crime scene

Case Study: Duchesse de Praslin

• Francoise, the Duchess of Praslin, was born on April 14, 1807
  • She married the Duke of Praslin, Charles, at age 17
• Fanny and Charles had 10 children, but their relationship soured after marriage
• The Duke began an affair with their nanny
• Fanny was infuriated, threatened divorce, and threatened to take the children
• In August 1847, Fanny was found dead with hair clutched in her hand and more samples strewn around
• Her husband, Charles, was the prime suspect
  • He committed suicide by taking arsenic

Biology of Hair

• All mammals have hair, which is one of their distinguishing features
• Humans, too, have hair all over their bodies
• The main purpose of hair is to help regulate body temperature by insulating the body
  • In some animals, hair provides camouflage
  • Thick hair in mammals is called fur
• Other purposes of hair include protection from UV radiation and providing signals to other animals
  • These signals can be warnings, indications for mating, or sensory functions
• Hair can be transferred during physical contact and tie people to crime scenes

Life Cycle of Hair

• Hair growth occurs everywhere on the human body except a few select locations
• Hair growth follows three distinct phases: anagen, catagen, and telogen
• Anagen is the growth phase, where hair actively grows, lasting up to 5 years at ~85%
• Catagen is the phase where the papilla detaches, the shaft moves upward, and lasts for about two weeks at around ~1%
• Telogen is when the hair remains dormant, breaks from the root, and gets shed, lasting 1 to 3 months at ~14%
• Each hair on the human body is in its own stage of development and will restart once finished

Structure of Hair: Follicle

• There are two parts to hair: follicle and shaft
• The follicle is a club-shaped structure below the skin, attaching to the papilla at the end and is considered living
• The papilla is a network of blood vessels that support nutrients
• The papilla is surrounded by the sebaceous gland
  • The gland secretes oil, which conditions the hair

Hair: Ripped or Torn

• In a crime scene, if hair has been forcibly ripped from the victim, the hair follicle may still be present
  • This includes the follicular tag (tissue still attached to the root)
  • The tag usually contains blood and tissue for DNA comparison
• Hair that falls out naturally will still have the original club-shape of the follicle
• Forcibly removed hair may have a stretched-out appearance in the follicle, along with a follicular tag

Structure of Hair: Shaft

• The hair shaft is the area of hair seen above the skin, made up of protein that makes it strong and flexible
  • Shaft is the dead part of the hair
• The three layers of the hair shaft include the medulla, cortex, and outer cuticle
• The medulla is the center of the shaft, which varies among individuals
• The cortex surrounds the medulla and is the source of water uptake
  • This is the thickest part containing most of the pigment to give color
• The outer cuticle is the outer layer composed of lipids, which repel water
  • Cells point towards the older ends of hair

Types of Medulla

• The five different patterns of medulla include continuous, interrupted, fragmented, solid, and none
• Continuous is one unbroken line
• Interrupted, AKA intermittent, is broken into regular intervals
• Fragmented, AKA segmented, is broken into irregular intervals
• Solid medulla and cortex are the same pigment color
• In the none type, there is a lack of separate pigmentation in the medulla

Medulla: Animal v. Human Hair

• In animals, the medulla is much larger than in humans
• Determining the medullary index can determine if a hair came from an animal or a human
• The medullary index is the diameter of the medulla divided by the diameter of the hair
• Measurements for the medullary index:
  • If less than 0.33, then it came from a human
  • If greater than 0.5, then it came from an animal

Hair Type

• Andre Walker, Oprah Winfrey's hair stylist, created a classification of four hair types
• The four types of hair include straight, wavy, curly, and kinky
• Straight hair is the most resilient, hard to curl, and naturally the most oily
• Wavy hair is in between straight and curly and becomes easily frizzy
• Curly hair has curls with an S-shape or Z-shape
• Kinky hair as tight coils of curls with an O-shape or Z-shape
• Forensics traditionally use three categories: wavy/kinky, curly, and straight

Racial Determination

• It is possible to identify a human hair from a racial group
  • These identifications are generalizations and may not apply to every individual
• European hair:
  • Generally straight, wavy, or curly
  • Can be oval or round cross section
  • Blonde, red, brown, or black
• Asian hair:
  • Almost always straight
  • Round cross section, with a larger diameter
  • Brown or black
• African hair:
  • Generally curly or kinky
  • Oval to elliptical cross-section
  • Brown or black

Case Study: Kirk Odom

• On February 24, 1981, a woman was attacked in her apartment
  • She was blindfolded, but got a short glimpse
• The victim worked with police to provide a sketch of the suspect
  • A photographic lineup was unsuccessful
• On April 3, 1981, a police officer thought Odom resembled the sketch
  • A photographic lineup with Odom was organized
  • The victim tentatively identified him
• During the criminal trial, an expert testified that hair left by the suspect matched Odom’s hair
• DNA testing in 2014 resulted in Odom not matching the DNA at the crime scene

Types of Hair

• There are six different types of hair on a human body categorized by their cross-sectional shape
• Head hair tends to be circular or elliptical, and is the longest of all types
• Eyebrows and eyelashes are circular with tapering ends
• Beard & mustache hair is triangular, thicker, and may be cut
• Underarm hair is oval or triangular
• Body hair is oval or triangular
• Pubic hair is oval or triangular; coarser & wiry

Equipment: Hair Analysis

• The most common piece of equipment to analyze hair is a comparison microscope
  • It is possible to compare a known sample (suspect) with an unknown sample (crime scene hair).
• An investigator needs to collect at least 25 hairs per sample as there is so much variation, even on an individual
• The two most valuable hairs for investigators are head hairs and pubic hairs
  • Due to the nature of environmental damage, get a sample of head hair as soon as possible
  • Pubic hair has less damage and can be taken up to a year afterward

Dyes & Artificial Treatment

• Coloring hair, with bleach or other dyes, is extremely common in humans, especially women
• Dying hair a different color changes the color of the shaft as well as the cuticle and cortex
  • Artificial dyes show a sharp line where the hair color changes immediately from the dye, while hair that has been sun-bleached is more gradual
• Forensic scientists can determine if the hair has been artificially dyed
• If the entire hair has been recovered, scientists can determine when the hair was last dyed
  • Hair grows at a rate of 1.3 cm per month
  • Dividing the length of dyed growth by 1.3 cm can provide the number of months

Case Study: Raymond Santana

• On April 19, 1989, a woman jogging in Central Park was attacked
  • Her skull was fractured, and she lost 75% of her blood in her body
• Police zeroed in on five juvenile suspects who had been in the park during the attack
  • The suspect confessed after prolonged interrogations
• During the trial, an expert testified that hair left on the victim matched one of the suspects
• After serving five years in prison, Raymond Santana’s DNA was tested, and it did not match the suspects DNA
  • It matched another person already in the system- Matias Reyes
  • Reyes had attacked a woman two days earlier with a similar pattern

Unique Determinations

• Geographic determination: Hair samples can give ranges of geographic areas
  • Rainwater has different isotopes according to the location in the US
  • Water becomes incorporated into your hair
• Occupational determination: May be able to narrow occupations if exposed to hazardous materials
• Substances: Hair grows from the skin and will absorb chemicals, and being able to be detected through analysis
  • Testing can provide evidence of drugs or poisons
  • Hair analysis can show up to 3 months of drug use
  • Urinalysis is only effective for 3 days

DNA Testing & Hair

• There are three different types of DNA analysis for hair samples: nuclear DNA, mDNA, and Y-STR DNA
• Nuclear DNA:
  • Comes from the nucleus
  • The root must be attached to provide DNA evidence
  • Present in hair shafts, but degrades readily when hair sheds
• mDNA:
  • Comes from mitochondria
  • Can only differentiate individuals from maternal lines
  • Siblings cannot be distinguished
• Y-STR DNA:
  • Chromosomes are inherited from father to son through generations
  • Can link male relatives but can't differentiate individuals.

Crime Scene Hair Collection

• Hair can be collected from a crime scene and compared against known samples to identify
• It can be picked up with forceps, vacuum, sticky tape, or swept
• Hair guidelines include:
  • Package samples from different areas separately
  • Submit in a druggist fold then an evidence bag
  • Take at least 25 hairs from a suspect for sampling
  • Acceptable samples are from head hair or pubic hair

Issues with Hair Samples

• Hair cannot be used to identify one person unless it includes the papilla and can produce DNA results
• Hair is class evidence that can be used for groups of people
  • For example, if a suspect leaves blonde (dyed) hair at the crime scene, the suspect pool is narrowed to all individuals who dye their hair blonde
• Prior to DNA evidence, it was common practice for forensic scientists to use the term hair matches
  • The hair is deemed consistent instead of a direct match
• Starting in the 1990’s, the FBI conducted a study that showed people previously convicted with hair evidence had an 11% error rate
  • DNA did not match the suspects

Case Study: Timothy Bridges

• On May 14, 1989, Modine Wise was badly beaten when a burglar broke into her home
  • Wise was elderly and could not see well
  • She could not describe her attacker
  • She died 13 months later
• Three informants with prior criminal records claimed that Timothy Bridges confessed to attacking Modine
• An FBI-trained hair analyst testified that crime scene hair matched Bridges
• Crime scene DNA was tested, and it did not match Timothy Bridge’s DNA. He was released after 25 years

Paint

• Paint is a colored substance spread over a surface that dries to leave a thin decorative or protective coating
• Paint is one of the most common items forensic labs receive because of millions of painted objects
• Paint evidence is commonly found in:
  • Hit and runs where someone dies from being hit by a car
  • Burglaries where tool marks are found used to pry open a door

Automobile Paint

• Forensic scientists can sometimes identify a vehicle’s make, model, and color by examining paint left at hit-and-run fatalities
• Automobile paint has four layers -Electrocoat Primer
  • The first layer on steel cars, providing protection from corrosion; ranges from black to gray -Primer Surface
  • Covers any imperfections and is a variety of colors -Basecoat
  • A unique color that creates the visible see color -Clearcoat - A clear layer on top protects the basecoat

Analysis of Paint Evidence

• Most paint specimens sent to a forensic lab are not unique enough to identify a single source
  • The evidence will be “consistent with” if matched
• The best way to analyze paint specimens is through comparison microscope
  • Known and unknown/crime scene samples should be compared
• If a paint sample layers, they can be said to be consistent and likely from the same source
• Numerous paint colors for automobiles exist, with some unique to the manufacturer

Case Study: Gary Ridgway

• Gary Ridgway was one of America’s most prolific serial killers -Convicted of murdering 49 women in Washington state
• Gary worked as a spray painter at the Kentworth truck factory for decades, including during his murders
  • Gary was identified through DNA evidence in 2001
• His clothes and the victims' clothes were checked for trace evidence, and microscopic paint evidence was found on both
• Paint evidence was linked to Inron paint, not available to the public, used at the Kentworth truck factory plant

Soil

• Soil is the upper layer of earth in which plants grow
• Soil is made up of rocks, minerals, animal matter, vegetation, and decaying matter
• The three textures are:
  • Sand has extremely coarse (large) grains.
  • Clay has extremely fine (small) grains and is sticky when wet.
  • Silt has a medium particle size that is gritty

Collection of Soil Evidence

• Collect any items with soil found at a crime scene, such as:
  • Floor mats
  • Tires
  • Shoes
  • Tools
  • Clothing
• To collect large amounts of soil, use a razor blade
  • Use tape for smaller amounts
• Always collect soil in the area of interest at 3 ft and 15 ft from the area; then, store into containers, jars, or plastic cups with their lids

Forensic Examination of Soil

• After collecting, soil samples must be dried for accurate comparison
• Identify soil color using the Munsell Soil Color Chart as the first step
• Use a microscope to identify plant, animal, and artificial debris next
• The more rare items found in the soil and their combination, the higher evidentiary value
• The more unique the soil, the stronger the link between known and unknown soil samples

Case Study: Australia Double Murder

• In September 2000 in Australia, a woman and her son went missing
  • The next day, her car was found over 100 miles away with a bloodstained shovel
• A soil scientist examined the shovel to give clues on where the bodies were located
• Clues included:
  • Large angular quartz samples only found in soil depth
  • A mix of iron oxide and clay, which was wet
  • A lack of plant organic material meant it came from deep soil
• Geological maps led police to narrow down the search in the Oakbank Quarry, samples were taken to match the shovel
  • Found both near a large pond in the quarry
• The husband was interrogated and confessed to the double homicide

Glass

• Glass is very commonly found in crime scenes, especially burglaries and hit and runs
• An amorphous solid with a random structure, naturally occurring from volcanic magma
• Glass softens rather than melting sharply at a distinct temperature and is very useful
• Common glass uses:
  • Windows
  • Windshields
  • Tableware
  • Glass art
  • Optics

Types of Glass

• Soda-lime
  • The most common type due to cheapness
  • From clear to green
  • Often used in window glass, bottles, and jars
• Soda-lead
  • Fine tableware and art objects
  • Often used because of its brilliance
    • Has lead, making it dangerous for containment
  • It can range in color because of the metals added
• Borosilicate
  • Is heat-resistant and chemical-resistant
  • Can be used for lab glassware and cooking
    • Known as Pyrex
• Silica
  • Used for deep sea diving and halogen lamps
• Tempered
  • Safety glass for car side windows - Designed to shatter into tiny sharp edges
  • Four times stronger than regular window glass
• Laminated
  • Safety glass for car windshields
  • Consists of two layers of glass with plastic in the middle - The glass shatters and holds together
  • Bulletproof glass is made similarly with multiple layers

Physical Properties of Glass

• Two valuable physical properties: density and refractive index
• Density
  • Volume divided by mass is the formula
  • Obtain the mass of the glass sample
  • Put a sample into water, find the change in volume
• Refractive Index
  • The property of light bending due to velocity change when traveling from one environment
  • The FBI has 2,000 samples to compare to crime scenes

Forensic Examination of Glass

• Two goals of forensic scientists examining glass are to:
  • Identify the type.
  • Match to a source, if possible, using fractures and patterns
• It is possible to take unknown glass samples from a crime scene and compare known samples using a comparison microscope
• Unique characteristics exist through:
  • Surface striations or marks
  • Surface contaminants such as paint
  • Hardness
  • Thickness

Glass Fractures

• Fractured glass can be analyzed to determine force and direction
• Criminals may stage a burglary and shatter glass from the inside
• Bullet holes have a wider exit hole when compared to the entrance hole
• Radial fracture
  • Radiates outward in straight lines
• Concentric fracture
  • Circles the opening in a circular pattern

Glass Fractures: Direction & Sequence

• Stress fractures are known as conchoidal fractures, radiating away from impact
• Conchoidal fracture - Curved breaks looking like concentric ripples
• Sequence can be determined of multiple bullet holes
  • Fractures are terminated at the initial fracture
    • An initial bullet stops fractures that happen after

Collection of Glass

• Glass is commonly broken during the commission of a crime
  • Fragments of glass are found on the hair or clothing of a suspect
• The direction of impact determines what part to collect
• Mark the collected glass with which part of the frame faced inside
• Collect known samples
• Common collection methods include:
  • Placing large fragments into cotton or butcher paper
  • Placing small fragments into a druggist's fold
  • Ensure minimal movement during transport so new breaks do not occur
  • Sharp hazard should be labeled on the package