Forensic Techniques

What is Forensic Science?

• Forensic comes from the Latin word forensis.

• It means: for public discussion or debate.

• Forensic science is science used in public, in a court or in the justice system. 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 involved in all

aspects of criminal cases. • The forensic scientist's goal is to use all

available scientific information to determine the facts and, subsequently, the truth.

• The forensic scientist might determine: – The validity of a signature on a will, – If a corporation is complying with environmental

laws, – The origin of physical evidence at a crime scene.

Forensic Scientists•The facts developed by

forensic scientists are based on scientific investigation, not circumstantial evidence or the sometimes unreliable testimony of witnesses.

•The work of the forensic scientist can prove the existence of a crime or makes connections to a crime.

Forensic Scientists

• The forensic scientist provides information and expert opinion to investigators, attorneys, judges, and juries which is helpful in determining the innocence or guilt of the accused.

• Forensic scientists work closely with police officers, sheriff's deputies, prosecuting and defense attorneys, DEA, CIA, and FBI agents, immigration workers, and crime scene investigators, to name a few.

Techniques

• Forensic scientists use a variety of techniques in their investigations.

• The next 8 slides provide examples of forensic techniques.

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.

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.

Autopsy

• Done by a medical examiner• To determine cause of death• Includes external exam and photos• Followed by extensive internal exam:

– Organs are removed, weighed and examined

– Tissues and fluids are analyzed for abnormalities, presence of drugs, etc.

DNA Typing

• DNA code varies from one individual to the next

• Scientists can link a strand of DNA to an individual

• DNA can be identified from hair, blood, or body fluid stains

• Provides powerfully compelling evidence

Forensic Anthropology

• Examination of skeletal remains• Tells if male or female, how the

person lived, past illness or debilitation, clues to occupation

• Bones can tell us:– Age at time of death– Gender– Race– Height

Odontology

• 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 useful in determining a

subject’s age

Blood

• Chemical test can determine if substance (stains) is really blood

• Another test determines if it is animal or human blood

• Can determine gender from blood evidence

Forensics and investigation

• American’s Missing– 2,300 people are reported missing each day– Reports of missing persons have increased

sixfold in the past 25 years, from roughly 150,000 in 1980 to about 900,000 this year

• Forensic Science- involves finding the facts of the case that uses technology to uncover scientific evidence

• Forensic Medicine-applied to medical science to legal problems and multiple science specialties