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. 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. Match knife to cutting characteristics seen/recorded/found 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; earliest technique 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 Most recent technique 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 (Luminol) test can determine if substance (stains) is really blood Another chemical (Precipatin) test determines if it is animal or human blood Can determine gender from blood evidence; by Barr Bodies on Neutraphils