Introduction to Forensic ScienceChapter 1

Chapter 1 Objectives

• To be able to define forensic science and describe its various areas

• To be able to describe the major events in the history of forensic science and relate them to modern-day practice

• To be able to describe the duties of a forensic scientist

• To be able to describe the organization of federal, state, and local forensic science laboratories

• To be able to diagram and describe the flow of evidence through a crime laboratory

• To be able to describe the qualifications for becoming a forensic scientist

• To be able to get information on careers in forensic science

FORENSICS• Today we use the term to

mean the methods of science applied to matters involving the justice system

• Which sciences are forensic sciences?– Any science can be a forensic

science if it has some application to justice

– Criminalistics, Pathology, Anthropology, Odontology, Engineering, Entomology

CRIMINALISTICS• The term can be used to describe the

comparative forensic sciences such as fingerprints, questioned documents, firearms and toolmarks

• Most commonly, however, criminalistics refers to the myriad of types of physical evidence generated by crime scenes– Illicit drugs, blood and DNA, fire and explosive

residues, hairs and fibers, glass and soil particles, paints and plastics, fingerprints, bullets, and much more

PATHOLOGY• Forensic pathologists determine the cause and

manner of death in cases where someone dies under suspicious circumstances

• Cause of death – event that directly causes death– Stroke, drug overdose, auto crash, poisioning, etc.

• Manner of death – the type of death (four only)– Homicide, natural, accidental, and suicide

• Autopsy (or postmortem examination) is used to make these determinations

• Pathologists work for medical examiners or coroners (varies by state)

ANTHROPOLOGY• Forensic anthropologists work with skeletal

remains• If human, they determine from what part of the

body the bone originated• If they have the correct bones:

– Gender, age, racial characteristics, and even socioeconomic status can be determined

• If there is an injury to a skeleton or major bones, the cause of the injury or death can be determined

• It is also possible to build a face onto a skull using clay and pegs of various sizes

• Facial reconstruction helps find missing persons

ODONTOLOGY• Odontology is a fancy name for dentistry• Bite marks on a victim or other object can be

matched to a suspect• Forensic odontologists can also help identify

remains from disasters such as plane crashes– Postmortem dental records are taken and matched

to x-rays taken before death

• It is also possible to distinguish causes of facial injuries– Falling down the stairs vs. being struck by an

object

ENGINEERING• Forensic engineers can be valuable in cases

where something has gone wrong with a mechanical or structural entity or in cases of automobile crashes

• Failure analysis is one of the major contributions that forensic engineers make to the justice system

• The majority of the work of forensic engineers is in the investigation of traffic crashes– Accident reconstruction is used to determine speeds,

directions of impact, and who was driving the vehicle at the time of impact

ENTOMOLOGY• Flies (usually blowflies) are usually the first to

arrive at a crime scene• Flies and other insects lay their eggs in decaying

flesh– Different insects do this at different times– Other insects such as beetles and wasps will attack and

feed off the insects and eggs

• This parade of visitors takes place at surprisingly consistent time intervals

• Forensic entomologists can estimate the postmortem interval (how long ago death occurred)

• If a person has been poisoned or has overdosed, flies and other insects will ingest this as well

Who Are Forensic Scientists?• Two types:

– Enlisted (sworn police officers)– Civilian

• As forensic science became more technical, civilians were hired because it became difficult to recruit scientists to be police officers

• Forensic scientists have very little function in evidence collection and rarely attend crime scenes

• Forensic scientists have two main duties:– To analyze evidence– To testify in court

Testifying In Court

• Lay witnesses testify as to what they have perceived with their five senses– They are not to give their opinions!

• Expert witnesses have knowledge or skills from education or experience that qualify them to give opinions and draw conclusions

• The judge decides if expert testimony is needed and who is qualified to offer it

The U.S. Forensic Science System• There are about 400 forensic science laboratories

in the U.S.• Most federal crime labs are in the Department of

Justice under the control of the attorney general• The FBI is know for having some of the most

prestigious forensic science laboratories in the world

• The DEA has labs that analyze seized illicit drugs• The secret service has labs to prevent harm to

protected people and to prevent counterfeiting and credit card fraud

The U.S. Forensic Science System (2)

• The Department of the treasury has crime labs

• The BATF labs have some of the world’s leading experts in fire and explosive analysis

• IRS crime labs specialize in the area of questioned documents – handwriting, typewriting and printers, inks, and papers

• The Dept. of the Interior has crime lab to investigate poaching and hunting

• Each of the 50 states has a public crime lab system and most have locally controlled facilities

Private Forensic Crime Laboratories• Private labs

usually work for the defendants– Only the

prosecutor has access to the local or state public laboratory

•The private labs perform a service to the criminal justice system by providing resources for those accused of crimes

Organization of Forensics Labs

• Typical forensic science labs have – An intake section– Analysis areas– Other sections

INTAKE SECTION• An intake officer logs evidence into LIMS and

affixes a barcode (Laboratory Information System)

• Chain of custody for physical evidence must be authenticated– There must be proof that the evidence seized at a

crime scene is the same evidence that appears in court– An improper chain of custody can be grounds to

render evidence inadmissible

• Considerations are made before testing so that one test does not ruin the conditions for another– A gun may need to be test fired, fingerprinted, and

have blood removed. The order is important!

ANALYSIS AREA

• This is the familiar laboratory setting

• Each scientist will have a designated area of the lab for evidence handling

• There are lots of instruments, glassware, implements, and scientists in white lab coats and safety glasses

OTHER LAB SECTIONS• Some labs may have a garage where cars can

be kept for inspection and searching

• Many firearms sections have huge stainless steel tanks that are full of water– These are used to test-fire weapons for comparison

with bullets or cartridges from crime scenes

• Some large labs have collections of seized weapons as well as ammunition

• There may also be interrogation rooms where polygraph tests are performed

CAREERS

• Becoming a forensic scientist requires education and training– Crime lab forensic scientist– Forensic pathologist– Forensic anthropologist– Forensic odontologist– Forensic Engineer

Crime Lab Forensic Scientist

• Entry level requirements include a bachelor’s degree in chemistry, biology, or forensic science and 1-2 years of experience or a master’s degree with less experience

• The job market is very competitive and a master’s degree is preferred

Forensic Pathologist

• Graduate from college with an excellent academic record (4 years)

• Graduate from medical school (4 years)

• Complete a residence in pathology (4 years)

• Complete a residency in forensic pathology (1 year)

Forensic Anthropologist

• Few crime labs can afford to hire a full-time forensic anthropologist

• A lab may hire you full time if you have another specialty (trace evidence, DNA typing, etc.)

• Most obtain a Ph.D. and teach at a university and handle cases part-time

Forensic Odontologist

• This is similar to the route for a forensic pathologist except that you would complete dental school instead of medical school

• There are very few residencies in forensic odontology

• You would need to work with the police on an as-needed basis

Forensic Engineer

• Require an education in engineering (the more the better)

• Usually, Ph.D.s are in demand

• Most forensic engineers have their own companies that are hired by prosecutors or defendants