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Notes on Forensics
Forensics
What is forensic medicine?
• Latin word - forensics
• Means public discussion or debate
• Science used in justice system for legal
purposes
• Facts based on scientific investigation
• Goal is to determine facts and truth
• Uses multiple science specialties
Forensic Anthropology
Skeletal anatomy
• 206 bones
• Man = 12 pounds
• Woman = 10 pounds
What bones show
• How person lived
• Debilitation illnesses (rickets, polio, healed
fractures)
• Right handed or left handed
• Clues to occupation
Forensic Anthropology
Questions about skeletal remains
• Age of person at time of death
• Sex of person (skull and pelvis)
• Race
• Height
Odontology
1. Characteristics of teeth after death
a. No other part lasts longer
b. In fires, teeth usually only means to ID remains
c. No two people have identical teeth
2. Requirements for identification
a. Need dental records
b. Dentists chart five surfaces of each tooth in a
grid (odontogram)
c. Can also provide “bite mark” evidence
3. Teeth useful in determining subject’s age
Autopsies
Definition and Purpose
• To see for oneself
• Surgical operation done on a dead body
• To learn about person’s health and cause of
death
Legal Requirements
• Coroner
• Medical examiner
• Pathologist
Autopsies
Reasons for autopsy
• Determine which disease or injury caused
death
• Diagnosis - confirmation and understanding
• Evaluate possible public health issue
Preparation
• If not required by law, permission needed
from next of kin
• Legal consent form
Autopsies
Procedure
• Complete medical history and review of records
• External physical exam
•Body tag
•Weight and height
•Clothing and valuables identified
•Scars, tattoos, injuries, wounds, bruises recorded
•Foreign objects noted
• Photos and x-rays taken, if needed
Autopsies
• Complete internal exam
• Dissection of head and abdomen
• Organs removed, weighed, measured, and
examined
• Tissue samples examined under microscope
• Fluid samples tested for drugs, infection
• After autopsy complete, legal death certificate
Results
• Natural death – disease or old age
• Unnatural death – unnatural, unexpected, or
unusual cases
Autopsies
Methods to determine time of death
• Traditional indicators
• Rigor mortis
Begins three hours after death in face and
eyelid muscles
Takes twelve hours to affect entire body
Process reverses after 36 hours
• Lividity (hypostasis)
Visible 30-60 minutes after death
Red cells settle and skin below turns red
In 6-10 hours, color becomes permanent
Autopsies
• Body temperature
Falls at rate of one degree per hour
Obesity and warm environment slows
cooling
• None of the above are totally reliable and can
be manipulated
Serology
Blood type

Four types (A, B, O, and

Rh factor

Female cells have Barr
Body
AB)
Serology
Criminology
 Kastle-Meyer test to determine if it is indeed
blood
 Precipitin test – determines animal or human
blood
 Can determine type and gender from blood
 Provides reliable and informative evidence
DNA
What is DNA?

Nucleus of cells contain RNA/DNA

DNA = deoxyribonucleic acid

Nucleus has 23 pairs of chromosomes made
up of DNA

Within each pair, one chromosome from
sperm and one from egg
DNA Typing
What makes DNA individual?
 Four chemicals:
Adenine, Guanine,
Cytosine, and Thymine
 Chemical strung together=DNA code
 Some sections of DNA
vary from individual
to individual
 Scientists can link a strand of DNA to a given
individual
DNA Typing
Criminal investigations
 Specimens: blood, hair, bloodstained clothing
 Provides powerfully compelling evidence
DNA Typing
DNA Typing
DNA Typing
DNA Typing
DNA Typing

What are the chances that the DNA profile of a
random person would match the crime scene DNA?
Probe A
Probe B
Probe C
Probe D
1%
5%
10%
2%
Multiply the individual probabilities:
0.01 x 0.05 x 0.1 x 0.02 = 0.000001
1 person out of every 1
million could have left the
DNA at the crime scene.
Other Tools
Firearms and Toolmarks
• Typically, this includes matching bullets to
the gun that fired them.
• Toolmark identification involves the
identifying characteristics between tools,
such as a pry bar, and the object on which
it is used, such as a door frame.
• Also included in the category are
explosives and imprint evidence.
Other Tools
Forensic Profiling
• When a specially trained psychiatrist or
investigator can examine certain crime
scenes to come up with a personality
profile of the offender.
Document Examination
• This discipline involves all special
relationships that may exist between
document and inscription and how it
relates to a person or sequence of events.
• This includes forgery, counterfeiting, and
handwriting analysis.