Notes on Notes on ForensicsForensics

ForensicsForensicsWhat 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 AnthropologyForensic Anthropology

Skeletal anatomy• 206 bones• Man = 12 pounds• Woman = 10 poundsWhat bones show• How person lived• Debilitation illnesses (rickets, polio, healed fractures)• Right handed or left handed• Clues to occupation

Forensic AnthropologyForensic Anthropology

Questions about skeletal remains• Age of person at time of death• Sex of person (skull and pelvis)• Race• Height

OdontologyOdontology1.1. Characteristics of teeth after deathCharacteristics of teeth after death

a.a. No other part lasts longerNo other part lasts longerb.b. In fires, teeth usually only means to ID In fires, teeth usually only means to ID

remainsremainsc.c. No two people have identical teethNo two people have identical teeth

2.2. Requirements for identificationRequirements for identificationa.a. Need dental recordsNeed dental recordsb.b. Dentists chart five surfaces of each tooth in Dentists chart five surfaces of each tooth in

a a grid (odontogram)grid (odontogram)

c.c. Can also provide “bite mark” evidenceCan also provide “bite mark” evidence3.3. Teeth useful in determining subject’s ageTeeth useful in determining subject’s age

AutopsiesAutopsies

Definition and Purpose• To see for oneself• Surgical operation done on a dead body• To learn about person’s health and cause of

deathLegal Requirements• Coroner• Medical examiner• Pathologist

AutopsiesAutopsies

Reasons for autopsy• Determine which disease or injury

caused death• Diagnosis - confirmation and

understanding• Evaluate possible public health issuePreparation• If not required by law, permission needed

from next of kin• Legal consent form

AutopsiesAutopsiesProcedure• 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

AutopsiesAutopsies• 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 certificateResults• Natural death – disease or old age• Unnatural death – unnatural, unexpected, or

unusual cases

AutopsiesAutopsiesMethods 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

AutopsiesAutopsies

• 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

SerologySerology

Blood typeBlood type Four types (A, B, O, and Four types (A, B, O, and AB)AB) Rh factorRh factor Female cells have Barr Female cells have Barr

BodyBody

SerologySerology

CriminologyCriminology Kastle-Meyer test to determine if it is Kastle-Meyer test to determine if it is

indeed bloodindeed blood Precipitin test – determines animal or Precipitin test – determines animal or

human bloodhuman blood Can determine type and gender from Can determine type and gender from

bloodblood Provides reliable and informative Provides reliable and informative

evidenceevidence

DNA DNA

What is DNA?What is DNA? Nucleus of cells contain RNA/DNANucleus of cells contain RNA/DNA DNA = deoxyribonucleic acidDNA = deoxyribonucleic acid Nucleus has 23 pairs of Nucleus has 23 pairs of

chromosomes made chromosomes made

up of DNAup of DNA Within each pair, one chromosome Within each pair, one chromosome

from from

sperm and one from eggsperm and one from egg

DNA TypingDNA Typing

What makes DNA individual?What makes DNA individual? Four chemicals: Four chemicals: AAdenine, denine, GGuanine, uanine,

CCytosine, and ytosine, and TThyminehymine Chemical strung together=DNA codeChemical strung together=DNA code Some sections of DNA Some sections of DNA vary from vary from

individual to individual to individualindividual Scientists can link a strand of DNA to Scientists can link a strand of DNA to

a given individuala given individual

DNA TypingDNA Typing

Criminal investigationsCriminal investigations Specimens: blood, hair, Specimens: blood, hair,

bloodstained clothingbloodstained clothing Provides powerfully compelling Provides powerfully compelling

evidenceevidence

DNA TypingDNA Typing

DNA TypingDNA Typing

DNA TypingDNA Typing

DNA TypingDNA Typing

DNA TypingDNA Typing

What are the chances that the DNA profile What are the chances that the DNA profile of a random person would match the of a random person would match the crime scene DNA?crime scene DNA?

Probe A 1%Probe B 5%Probe C 10%Probe D 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 ToolsOther 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 ToolsOther ToolsForensic 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.