QM Study Guide Review
Forensic Science
2015-2016
Vocabulary
• Vocabulary:
• Keratin
– A type of fibrous protein that makes up the
majority of the cortex of a hair
• Neutron activation analysis
– A method of analysis that determines the
composition of elements in a sample
Hair Shaft
Epidermis
Dermis
Hair follicle
Cuticle
Cortex
Sebaceous
Gland
Medulla
Papilla
Capillary
Chapter 3
• the formula for calculating medullary index.
– Diameter of medulla/diameter of hair
• How is it used to determine an animal hair
from a human hair?
– Animal hair has medullary index of 0.55 or higher
– Human hair has medullary index around 0.33
• Let’s Practice:
• What are some characteristics that can be
studied by looking at a hair and examining it
under a microscope?
– Color, pigment distribution, cuticle scale patterns,
medulla patterns, direction of top of hair, if
follicular cells are present
• Differences between an animal and human
hair
– Patterns of pigmentation, the medullary index and
the cuticle type.
• Rate of growth for a human hair
– 1.3 cm/month
– 0.44mm/day
• How can you use this information to determine an
estimated time of death or estimated time of drug
use?
– Divide the length of hair from scalp to area of interest by
the rate of growth for an estimated time of drug usage or
time of death.
– Let’s practice…
• A person was suspected of chronic drug use so a hair was taken to
be tested for presence of drugs. The person stated “I stopped
using drugs 2 months ago man.” Analysis of the hair revealed
traces of THC and cocaine at 2.6cm and beyond all the way to the
tip of the hair. Based on these results has the guy been clean or
off drugs for 2months?
– Yes, he has been off drugs for 2 months. Hair grows at an approximate
rate of 1.3cm per month and the drugs were not detected in the last 2
months of hair growth or 2.6cm. Evidence 2.6cm/1.3cm = 2 months
• Where can DNA be found on hair?
– Hair follicle or follicular tag
• What type of evidence is hair classified as?
– Class evidence, trace evidence, circumstantial
evidence
– If the hair follicle is present and DNA can be
extracted it can be used to identify an individual.
Chapter 4
• Direct transfer
– Evidence transferred from one source to another.
• Secondary transfer
– Evidence transferred from one source to another and then to another
source.
• Synthetic fibers
– Made from man made substances such as plastic
• Natural fibers
– harvested from plants, animals or mineral sources
• Yarn
– Fibers that have been spun together
• Monomer
– A mall molecule that may bond to more of the same units to become a
polymer
• What types of evidence can fibers be classified as?
– Trace evidence, class evidence and circumstantial evidence
• What types of information can be learned from fiber evaluation?
– Type of fiber, fiber color, number of fibers found may suggest the level
of violence in the crime, location of fibers, textile type, number of
different types of fibers.
• What major health hazard has asbestos been linked to?
– Lung cancer
• How can fiber evidence be used by forensic scientists to help link
multiple crimes to a suspect?
– Fiber evidence can link multiple crimes committed by the same
suspect(s) if matching fibers are found at more than one crime scene
or more than one victim. Example several serial killers have left
behind fiber evidence on the bodies of several of their victims. This
evidence along with other similarities among how the crime was
committed can be enough to get a confession, or a conviction.