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. 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 Specialties 1. Medical Examiner A medical doctor usually qualified as a forensic pathologist, in charge of death investigations

2. Forensic Toxicology The investigation of drugs and poisons in the body in cases of illegal drug use, drug abuse, poisoning and death. Lab tests are used that include gas or liquid chromatograph-mass spectrometer. Different chemicals will move through and exit at different times and eventually create a pattern in a graph that can be used to identify the chemical.

3. Forensic Pathologist Medical doctors who first study Pathology then Forensics. They carry out autopsies to document the cause and contributing factors to a death. They collect samples for Toxicology.

4. Forensic Anthropology Identifying and investigating skeletal remains. Typically not medical doctors, but trained as physical anthropologists, bioarchaeologists or primatologists. They can determine age by ossification of bones and teeth eruption. By analyzing isotopes in teeth they can determine where a person was born or spent their early years.

5. Forensic Odontology Using dental science in forensics. Used to identify an individual. Also used in bite mark evidence. (DNA has proved to be more accurate.)

6. Wildlife Forensic Science Techniques used for cases involving nonhuman biological evidence. It includes plants and animals in crimes with human victims. Evidence in cases involving illegal wildlife trade and cruelty to animals.