Forensic Science. What is Forensic Science? Forensic comes from the Latin word forensis. Forensic...

ForensicScience

What is Forensic Science?

Forensic comes from the Latin word forensis.

Meaning - for public discussion or debate.

Any science, used for the purposes of the law, is a forensic science.

Forensic Scientists

Television enhances the image of forensic science.

Forensic scientists are not involved in all aspects of criminal cases.

Goal - use all available scientific information to determine the facts &, subsequently, the truth.

Forensic Scientists

Scientific facts Based on investigation, not

circumstantial evidence or the sometimes unreliable testimony of witnesses.

Forensic scientists can prove the existence of a crime or make connections to a crime.

Works Closely With

State & Local Police & Sheriff Prosecuting and Defense Attorneys Immigration workers Crime scene investigators DEA – Drug Enforcement Agency CIA – Central Intelligence Agency FBI – Federal Bureau of Investigation

Types of Forensic Scientists

Criminalistics  - Engineering

  - General  - Jurisprudence   - Odontology   - Pathology/Biology   - Physical Anthropology  - Psychiatry & Behavioral Science   - Questioned Documents   - Toxicology

Locard Exchange Principle

Locard: director of the very first crime laboratory in Lyon, France.

Principle states that "with contact between two items, there will be an exchange

Perpetrator(s) of a crime comes into contact with the scene, they will both bring something into the scene and leave with something from the scene.

Every contact leaves a trace.

Eight Forensic Techniques

Firearms and Tool Marks Forensic Profiling Document Examination Autopsy DNA Typing Forensic Anthropology Odontology Blood

Firearms and Tool Marks

Matching bullets to the gun that fired them.

Tool Marks: ID characteristics between tools and the object it was used on

Pry bar and door with matching imprints

Explosives and imprint evidence.

FirearmsGunshot residue particle analysis pertains

to: Identification of bullet holes Estimation of range of fire Linking the suspect with the firing of a gun-

in-question

Forensic Profiling

Specially trained psychiatrist or investigator can examine crime scenes to develop a personality profile of the offender.

Sex Age Occupation Lifestyle  

Document Examination

This discipline involves relationships that between document and inscription and how it relates to a person or sequence of events.

Forgery Counterfeiting Handwriting analysis.

Document Investigation

Document examination case fall into the "white-collar crime" category

Include identity theft, forgery, counterfeiting, fraud, Questioned documents are often important in so

many different contexts and for so many different purposes.

May commit murder and forge a suicide note Document being produced directly as a part of a

crime

Autopsy

Post mortem exam determines: Manner of Death Method of Death Time of Death Place of Death

Death That Must be Reported & Investigated

Sudden or unexpected Suspicious circumstances Result of an injury of Accident

Natural death – disease or old age; Unnatural death – unexpected or unnatural

causes

Other Reasons for Autopsy

Diagnosis Disease Evaluate possible public health issue For example, the diagnosis of Alzheimer’s

disease can only be confirmed upon autopsy

Autopsy Process

Includes external exam and photos Tattoos, Scars, Birthmarks, etc.

Followed by extensive internal exam: Organs are removed, weighed and

examined Tissues and fluids are analyzed for

abnormalities & presence of drugs

Fluids Examined

Urine Semen Vomit Blood Stomach Contents Spinal Fluid Saliva

Medical Examiner

Has the legal authority to order an autopsy without the consent of the deceased person’s next of kin.

If not ordered by Medical Examiner, MUST have permission from next of kin.

DNA Typing

What is DNA? Nucleus of cells contain RNA/DNA DNA has deoxyribonucleic acid. Nucleus has 23 pairs of chromosomes made

up of DNA In each pair, one chromosome from sperm,

one from egg

DNA Typing

Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses.

The main role of DNA molecules is the long-term storage of information.

DNA Typing

What makes DNA individual? Four chemicals: Adenine Guanine Cytosine Thymine.

DNA Typing

DNA is often compared to a set of blueprints or a recipe, or a code

Contains the instructions needed to construct other components of cells, such as proteins and RNA molecules.

DNA Typing

Such examination can establish whether a given strand

is a strand of mammalian hair (vs. a synthetic or natural fiber),

is a strand of human hair Is from the head or another region (pubic) Was a living, growing hair at the time it

was separated Came from a particular race of persons

DNA Typing

Chemical strung together = DNA code.

DNA varies from individual to individual

Can link a strand of DNA to a given individual.

DNA Typing

Where DNA is Found at the crime scene Specimens – blood, hair, bloodstained

clothing Provides powerfully compelling evidence Look in the Bathroom

Forensic AnthropologyExamination of Skeletal

Remains

Total Bones in body, 206, Missing Bones? Man 12 lbs Women 10 lbs Gender Male or Female: Pelvic Girth Race: To Some Extent Height: Ratio of Length of Long Bones to

Height

Forensic Anthropology

Age at Time of Death: Size of Bones, Closure of Epiphysis

Cause of Death or Lifestyle: Wear and Tear, Disease Processes (arthritis, fractures)

How a person lived; Debilitating illnesses (rickets, polio, healed

fractures); Right or left handedness Clues to occupation

OdontologyExamination of Teeth

No other body part lasts longer In fires, often the only thing

remaining No two people have identical teeth Dental records are needed to

compare to the evidence Teeth can determine a subject’s age

Odontology

WEST WARWICK, R.I., Feb 22, 2003 Fire investigators have recovered the

remains of 96 victims of a Rhode Island nightclub and were working with forensic pathologists to aid identification efforts,

9 of the victims had been identified so far through dental records.

Blood - Serology

Blood type – 4 types

O, A, B, AB Rh Factor Female cells have Barr Body

Blood Groups

Blood Group Antigens Antibodies Can Give To Can Receive From

AB A & B None AB AB, A, B, O

A A B A & AB A & O

B B A B & AB B & O

O None A & B AB, A, B, O O

Blood

Kastte - Meyer Test can determine if substance (stains) is really blood

Precipiton Test determines if it is animal or human blood

Determine gender from blood evidence – female cells have Barr body

Determining Time of Death Rigor Mortis

Begins 3 hours after death in face & eyelid muscles

Takes 12 hours to affect entire body Process reverses after 36 hours. Rigor Mortis –

• Nysten’s Law: Rigor mortis affects first the muscle of the head and spreads toward the feet.

Determining Time of DeathLividity - Hypostasis

Visible 30 – 60 minutes after death

Red cells settle & skin below turns red

After 6 – 10 hours, color becomes permanent

Determining Time of DeathBody Temperature

Falls at the rate of 1 degree per hour Obesity and warm environment slows

cooling None of these are totally reliable and can

be manipulated

Forensic Entomologists

Forensic entomologists work in classrooms, research labs & in the field.

Practice of studying insects has existed for centuries, but there are so many areas of the field that remain largely untapped and promising.

If body has been moved How long the body has been there

Eyewitness Accounts

It used to be thought that memories were kind of like video tapes, but we now understand that all memories are reconstructions of events.

Memory is very plastic and malleable Memories are often manipulated and

greatly affected by our emotional state, personal prejudices and biases.