The Role of Criminalistics in Police Investigations

As soon as a crime is reported, an investigation is opened by the police or law enforcement agency with jurisdiction.

Police detectives and investigators use criminalistics in crime-scene investigations. Criminalistics is “the scientific study and evaluation of physical evidence in the commission of crimes.” Criminalistics plays a vital role in organizing crime scenes, helping victims, ensuring justice, and serving the public.

Criminalists cover a broad range of criminal justice jobs within the forensic science field that examine physical evidence to link crime scenes with victims and offenders. Criminalists are sometimes referred to as lab technicians or crime scene investigators, a term made famous by the TV drama CSI.

These criminalists consult with experts, examine and analyze a variety of evidence including fingerprints, hair, fibers, skin, blood, and more. The criminalists then use their analysis to determine answers to how a crime was committed.


A report from the National Institute of Justice outlined the role of criminalistics in police work. Criminalists investigate a variety of crimes, including domestic and aggravated assaults, burglary, robbery, sexual violence, and homicide.

Here are the basic functions completed by criminalists:

Establishing an element of the crime

  • It’s important for criminalists to establish proof that a crime occurred and to determine the cause and manner of death. Autopsies will help confirm the latter, while sending crime scene samples of blood, drugs, or semen, for example, could help determine the crime itself.

Identification of a suspect or victim

  • Fingerprint and DNA testing are two examples of forensic evidence that criminalists use to identify an offender.

Associative evidence

  • This type of scientific finding can help link the offender to the victim. Examples of associative evidence include hair follicles, blood, semen, fingerprints left on an object, foot impressions, and more.


  • Criminalists try to reconstruct how the crime happened using evidence from the crime scene. For example, certain evidence on a gunshot victim can discern the distance between a victim and the shooter.


  • Physical evidence from a crime scene can corroborate or refute information that investigators collect during interviews with witnesses, victims and suspects.


The FBI and U.S. Department of Justice distribute a guide for criminalist protocols when responding to a crime scene.

Here’s what the Justice Department recommends takes place.

Arrival/Initial Response

  • Upon arriving on the scene, criminalists should attempt to preserve the crime scene with minimal disturbance of the physical evidence.
  • Criminalists should make initial observations to assess the scene while ensuring officer safety and security.
  • They should react with caution. Offenders could still be at the crime scene and criminalists should remain alert and attentive until the crime scene is declared clear of danger.

Documentation and Evaluation

  • The investigator(s) in charge should set responsibilities, share preliminary information and develop investigative plans in compliance with department policy and local, state and federal laws.
  • Criminalists should speak with the first responders regarding observations from the crime scene before evaluating safety issues at the scene, establishing a path of exit and entry, and initial scene boundaries.
  • If multiple scenes exist, criminalists should establish and maintain communication with personnel at those sites.

Processing the Scene

  • Based on the type of incident and complexity of the crime scene, criminalists should determine team composition on site.
  • Criminalists will assess the scene to determine which specialized resources are required. For example, forensic examiners could be called to the scene, or a coroner to investigate a cadaver.

Completing and Recording the Crime Scene Investigation

  • Criminalists should establish a crime scene debriefing team, which enables all law enforcement bodies to share information about findings before the scene is released.
  • Criminalists determine what evidence was collected, discuss the preliminary scene findings with scene personnel, discuss potential forensic tests that will take place, and initiate any action required to complete the crime scene investigation.


The latest technological trends are making criminalistics an even more effective process. A report from the Netherlands Forensic Institute found that time is a chief factor in the scientific analysis of evidence.

Thanks to new technology, criminalists can perform some work previously done solely in labs at the crime scene, which allows for more accurate forensic investigation. It also allows for the study of large amounts of digital evidence in shorter time.


A career as a criminalist is one available with a degree in criminal justice. If this sounds like an interesting career path for you, then enroll today in Virginia Wesleyan University’s fully-online BA in Criminal Justice. Our accredited online program teaches you the real-world skills you need to succeed as a criminalist or in another criminal justice role, and our online format allows you to balance your education with your busy life.

Learn from highly qualified professors, including criminalists, in classes designed for your success. Apply today!