Skip to main content icon/video/no-internet
icon backReturn to Entries

Criminalistics

Criminalistics involves the application of science to law-related matters. It is a specialty that combines many disciplines: the efforts of chemists, biologists, toxicologists, and latent-print and questioneddocument examiners, among others. Different from criminologists, who address the causes, correction, and prevention of criminal behavior, criminalists analyze materials, or physical evidence, recovered from crime scenes. They work with police, lawyers, and probation officers in a combined effort to solve crimes.

Criminalists use scientific techniques and procedures in the laboratory, documented as good science practice within the scientific community, to analyze physical evidence, which is eventually used in a court of law to determine the guilt or innocence of a suspect. Possession of the evidence must be properly documented, with the dates and times the items were handled, and by whom. This is defined as the chain of possession, and it is imperative that this chain not be broken. If it is broken, the court will decide whether the evidence can be used or whether its integrity has been compromised. If the evidence is found to have been compromised, it cannot be used in a court of law.

From the Crime Scene to the Laboratory: Collection and Analysis of Physical Evidence

Preserving the Scene

The first step in properly processing a crime scene is to take swift and sure steps to see that the area is properly secured against any kind of disturbance. The police must then obtain a search warrant before anything else is done. Nothing should be touched, and no one should be allowed to enter except crime scene personnel trained in such investigations. A record should be kept of all persons entering the crime scene. If questions arise later, this record can be used to determine who was present.

Photographs show everything that is present at the crime scene. They should be taken from as many angles as possible to correctly convey relationships of evidence at the scene to items such as a body or weapon. Sometimes, crime scenes are too cluttered to be useful in pointing out specific items. In this case, sketches are used to show the important details and physical relationships.

The search for evidence is next. A drop of blood, a paper match, a fired bullet, a piece of paper, a thread of fiber, or strand of hair can all be physical evidence. Anything that is found is photographed and sketched for later use. Evidence that is transitory in nature should be collected first, such as gasoline that could evaporate. Then, the items are collected, tagged, and placed in proper containers, all packaged separately, to prevent the loss or contamination of evidence samples. A record is kept of all items collected at the crime scene before they are transported to the crime laboratory. All items must be marked by the person collecting them so that a proper chain of evidence can be maintained.

None

A forensic scientist or criminalist in a crime laboratory examines fragments of cloth from a car and clothing found at a scene of a hit-and-run incident. Criminalistics are increasingly more sophisticated in the use of technologies to examine physical evidence. Today, one of the cutting edges of forensic science is the examination of DNA evidence.

Copyright © Hulton-Deutsch Collection/CORBIS.

...

  • Loading...
locked icon

Sign in to access this content

Get a 30 day FREE TRIAL

  • Watch videos from a variety of sources bringing classroom topics to life
  • Read modern, diverse business cases
  • Explore hundreds of books and reference titles

Read next

More like this

Sage Recommends

We found other relevant content for you on other Sage platforms.

close

Have you created a personal profile? Login or create a profile so that you can save clips, playlists and searches

close
close
close Signed In to profile You are signed in as:
close
Logged in Institution Institution