Forensics Chapter 3: Hair Analysis Unit Review
How many hairs do you lose in a day? How much does your hair grow per month?
100 hairs/day 1.5cm/month
How many hairs does a person lose each day and how much does a person's hair grow in a month (on average)?
100 hairs/day half an inch/month
About how many hair follicles are you born with? Do you get more hair follicles as you get older?
5 million no, but hair density increases
How many hairs do the police need to collect from victims or suspects as a control sample? Why do they need to collect a sample?
50 hairs because of all the inconsistencies in human hair
How many types of hair do you have on your body?
6 head hair, beard/mustache hair, underarm hair, body hair, pubic hair, and eyebrows/eyelashes
What kind of information can you get from chemical tests like gas or liquid chromatography?
Amounts of toxins, poisons, drugs, heavy metals, nutritional deficiencies
Knowing that the ratio of the diameter of the medulla to the diameter of the entire hair is the medullary index, calculate the medullary index of a hair whose diameter is 110 microns and whose medulla measures 58 microns. Is this a human or nonhuman animal hair? Justify your answer.
MI = 0.53 nonhuman hair
A hair is found at a crime scene. The diameter of the hair is 120 microns and the diameter of the medulla is 85 microns. What is the medullary index of this hair and is it a human hair or nonhuman hair?
MI= 0.71 nonhuman hair
T or F: All types of hair on the body are structurally the same and are involved with temperature regulation.
False
T or F: Today, all forms of hair evidence are considered to be of little value in crime-scene investigations.
False
T or F: Hair can provide clues about someone's ancestry.
True
T or F: Technological advances such as chromatography and IRMS have improved the validity and reliability of hair analysis due to its objective analysis.
True
What is melanin?
a protein pigment found in epidermal cells, protect skin against radiation from the sun
A gossip blog published a photo of a famous baseball player using drugs at a party held 8 months earlier. The baseball player claims that the photo was manipulated, and he denies any drug use. a) Can drugs injected more than 8 months ago be detected in hair? b) If his hair measures 14 centimeters long and hair grows approximately 1.3 centimeters per month, will there still be evidence of drug use in his hair? Explain.
a) yes b) yes because his hair had to grow about to about 10.4 cm in 8 months meaning it was less than 14, therefore his hair was long enough for drugs to be detected
Why is it important to know which direction the scales of a cuticle point on a hair shaft?
so that you can tell which end of the hair was closest to the scalp - scales point from the part closest to scalp to farther away from scalp - important to know if you are figuring out when a person collected various chemicals in their hair shaft.
Summarize how to correctly collect hair evidence from a crime scene.
use a post-it, tape, or forceps and put into a paper bindle
Name two methods for collecting hair evidence.
use forceps, gloves, tape, sticky note, or vacuum to pick up hair. put in a small box, glass vial, or paper bindle (druggist fold).
Which factors are used to calculate the medullary index of the hair?
width of medulla and the width of the hair
What kinds of things can your hair hold in it that can be a record of what you did/ate/drank?
your hair holds chemicals that can identify and quanify drugs, toxins, heavy metals, and nutritional deficiencies
What is the pigment in hair?
melanin granules
What kind of DNA evidence can be obtained from the hair shaft?
mitochondrial DNA (mtDNA) - class evidence
How does hair help regulate the body temperature of mammals when it is cold outside?
muscles in the skin make the hair stand straight which traps pockets of air. air acts as an insulating layer.
How do you collect hair evidence if it is not firmly attached to clothing?
photograph first in situ (in place). use clean forceps to place hair into a small box or glass vial or a paper bindle. once in the lab, hair can be removed by plucking, shaking, and scraping surfaces or by placing clear tape or a post it over a surface.
Identify three characteristics of hair that can be used to distinguish one person's hair from another.
pigment in cortex, diameter, medulla pattern, texture, dyed or bleached or not
What are some of the characteristics of hair that can vary from person to person?
pigment in cortex, diameter, medulla pattern, texture, dyed or bleached or not
What is the medullary index? Be able to calculate it, given data, and be able to determine if a hair is human or nonhuman.
ratio of diameter of medulla to the diameter of entire hair human = less than or equal to 0.33 nonhuman = greater than 0.5
You pet your dog Rover before you come to school and get some of Rover's fur on your jacket. Once you get to school, a freshman runs into you on the stairs and the fur gets on his jacket. What is this process called?
secondary transfer
What is the significance of the Snowball the cat case to forensic science?
usage of snowball's hair was the first time animal hair analysis was used to convict a murderer
What kind of microscope can you use to look at a crime scene hair and a suspect hair at the same time?
comparison microscope
What is the medulla pattern that looks like one long line (----)?
continuous
Be able to identify the medulla patterns: continuous, interrupted (intermittent), fragmented (segmented), solid, none.
continuous, interrupted (intermittent), fragmented (segmented), solid, none
What kind of cuticle pattern is shown here? What animal would have this type of cuticle pattern?
coronal mouse, bat
Know the 3 basic cuticle scale patterns:
coronal (small rodents and bats), spinous (mink, seals, and cats), and imbricate (humans) and examples of animals/people that have that pattern.
Crime-scene investigators collected hair from a dead person's body. Is the hair human or nonhuman? Describe two ways that the investigators could distinguish human hair from animal hair.
cuticle pattern or the medullary index
What are the three parts of a hair shaft?
cuticle, cortex, and medulla
What characteristics of hair can you observe on 100X-400 X magnification of a microscope?
determine if hair is human or nonhuman, look at the medulla pattern, cortex pigmentation, and types of scales on the cuticle
Hair can be used to determine ...
diet, drug habits, and geographic history
What does dyeing your hair or bleaching it do to the hair?
dyeing hair changes the color of the hair shaft and gives it a painted appearance - easily detected - cuticle and cortex both take on the color of the dye. bleaching hair oxidizes the natural pigment, making it lighter, makes the hair brittle, disturbs the scales on the cuticle, and the peroxide can damage mtDNA.
Name three other kinds of hair a person has besides head hair.
eyebrow/eyelashes, body hair, beard/mustache hair, pubic hair, underarm hair
When did hair analysis become important as a forensic technique?
first recognizes in the late 1800s
Which part(s) of hair can be analyzed for nuclear DNA?
follicle (root)
What are the two main parts of a hair?
follicle and shaft
What are the two main parts of hair?
follicle and shaft
What is the medulla pattern that looks like dashes (- - -)?
fragmented (segmented)
How is fur different from hair?
fur is denser
What are some of the analytical techniques that you can use to examine hair?
gas and liquid chromatography, isotope-ratio mass spectrometry (IRMS), DNA (nuclear DNA and mtDNA), neutron activation analysis (NAA)
What is secondary transfer?
hair at crime scenes can stick to clothes, carpets, and other surfaces and be transferred to other locations
Animal hair can distinguished from human hair because animal hair ...
has a greater medullary index and more variation in the cuticle patterns
Which kind of hair typically has a thinner medulla: human hair or animal hair?
human hair
Be able to describe what happens when you are cold - why does your hair stand up?
if the outside temp is cold, muscles in the skin pull hair strands upright creating pockets that trap air. the trapped air provides a warm, insulating layer next to the skin.
Human hair has which type of cuticle pattern?
imbricate
What kind of evidence can we get from a hair with the follicle attached (containing nuclear DNA) and without the follicle attached (mtDNA)?
individual evidence (with follicle) and class evidence (without follicle)
Microscopic hair analysis ...
is used to exclude a suspect
Which analytical technique can be used to determine the location where a person lived, based on the elements in water and in their hair?
isotope-ratio mass spectroscopy
Why is bleaching your hair/getting highlights so hard on your hair?
it damages cuticle and makes hair brittle and can damage mtDNA
Why is hair strong and flexible?
keratin helices are connected by strong bonds between amino acids which make hair strong and resistant to decomposition - great for forensic science
The hair shaft is made of the protein _____________ which is made of up ______________ and has a _____________ shape.
keratin, amino acids, helix (spiral)
How do you collect hair evidence if it is firmly attached to clothing?
leave hair(s) intact on clothing, diagram and note the exact location of the adhering hair. photograph the hair. package the clothing (if dry) with the attached hair.
What characteristics of hair can you observe by macroscopic analysis?
looks at color, length, curliness, and which body region the hair came from
Know about the hair shaft:
made of the protein keratin in a helix shape with hydrogen bonds between amino acids.
What is the main purpose of hair? What are some other functions of hair?
main purposed is to regulate body temperature - keep the body warm by insulating it. it also protects the skin against sunlight, and acts as a sense organ
Understand the hair shaft analogy of a pencil:
medulla, cortex, cuticle
What is the medulla pattern that has no line throughout the center ( )?
absent (none)
When a hair follicle is connected to blood vessels and actively growing, what stage is that hair in?
anagen stage
Analysis of Napoleon's hair led to the discovery that he probably died because of what?
arsenic poisoning
Why do police collect about 50 hairs from a suspect instead of just one?
because hair can vary in color and texture on the same person so you need to get a good sample of all hair
Why does hair not easily decompose?
because hair has a tough outer coating
Which of the following characteristics is commonly found in Asian hair?
black medulla
Know that the cuticle:
can help distinguish between different species
In the Purrfect Match Forensic Files episode, Doug Beamish was found guilty of the murder of his wife. What important evidence linked him to the crime scene and why was this case important?
cat hair from snowball the cat was found on doug's jacket and at the crime scene. this was the first case where animal DNA was used to convict a person.
The period when hair is naturally shed is called the ____ stage.
telogen
What is the last stage in the life cycle of a hair and what happens in that stage?
telogen stage: hair is cut off from blood supply and is dormant/resting - hair is easily shed in this stage
Know the life cycle of hair and what happens in each stage: anagen, catagen, telogen.
the anagen stage is the stage of active growth when cells around the follicle are actively dividing and depositing materials within the hair. in the catagen stage, hair stops growing and the follicle recedes as blood supply is reduced. in the telogen stage, the hair follicle is dormant or resting and hairs are easily lost.
Be able to describe the characteristics of the cuticle, cortex, and medulla.
the cuticle is the outer coating composed of overlapping scales. the cortex is the protein-rich structure around the medulla that contains pigment. the medulla is the central core (not all hairs have this).
What part of the hair contains nuclear DNA?
the follicle (root)
Describe the structure of hair. Include in your answer the following terms: follicle, medulla, cortex, and cuticle.
there are two parts of hair: a follicle (with papilla and capillary blood supply) and a shaft. the hair follicle is a club-shaped structure in the skin and contains cells with DNA along with a network of blood vessels that supply nutrients to feed the hair and help it grow. the hair shaft is composed of the protein keratin. the outer coating composed of overlapping scales. the medulla is the central core; however, not all hairs have medullas. finally, the cortex is the protein-rich structure around the medulla that contains pigment.
Why do people think that Napoleon was poisoned by arsenic?
there were traces of arsenic in his hair
Summarize why forensic investigations compare an isotope analysis of someone's hair with the isotope signature of different locations.
they can identify where people lived based on the isotopes in your hair that came from your drinking water
What is the main purpose of hair on the body of mammals?
to regulate body temperature
