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Indian Peafowl Feathers. Credit: USFWS

Students and Educators


Crime Scene Investigator
Crime Scene Investigator. Credit: Illustrated by Bob Dawson © Kenneth Goddard

The Crime Scene Investigator … is typically (and there's a lot of variation here among federal, state and local jurisdictions) an unarmed, non-sworn (not authorized to enforce laws or arrest suspects) and non-scientific-degreed technician whose primary job is to:

  • respond to routine crime scenes
  • collect basic information from the first responding officer at the scene
  • set a scene perimeter
  • take a set of "over-all" photos from outside the scene perimeter looking in
  • make a quick search for potentially perishable evidence
  • take a set of "over-all" photos inside the scene perimeter
  • make a careful and methodical search for items of physical evidence
  • properly document, preserve and collect those items of evidence
  • make a scene sketch that includes the location of all evidence items
  • package and tag the evidence items
  • transport and transfer custody of the evidence to the crime lab
Forensic Scientist
Forensic Scientist. Credit: Illustrated by Bob Dawson © Kenneth Goddard

The Forensic Scientist … is typically an unarmed and non-sworn scientist who possesses a bachelor’s or master’s degree in forensic science or a related discipline, and who specializes in the examination and comparison of specific categories of physical evidence such as:

  • Drugs (controlled substances)
  • Serology (blood proteins) & DNA analysis
  • Toxicology analysis (drug metabolites, alcohol, poisons, etc)
  • Biological evidence analysis (seminal stains, saliva stains, etc)
  • Latent fingerprints
  • Questioned Documents
  • Firearms evidence and tool marks
  • Foot ware and tire track impressions
  • Trace evidence (hairs, glass fragments, paint chips, etc)
  • Arson evidence
  • Serial number restoration
  • Explosives evidence
  • Gunshot residues

Given the complexity of the instrumentation, analytical protocols, and related databases, it is rare for a forensic scientist to be qualified to conduct analytical work in more than two or three of these evidence categories.

And given the huge backlogs of analytical work that most crime labs face (it is not unusual for the evidence collected on a major investigation, such as a homicide, to be analyzed and/or compared weeks or even months after the initial crime scene investigation.  Accordingly, it is a rare crime lab that can afford to send forensic scientists out anything other than the most serious and/or complicated crime scenes.

Detective. Credit: Illustrated by Bob Dawson © Kenneth Goddard

The Detective … is typical an experienced, armed and sworn law enforcement officer whose primary job is to interrogate witnesses and suspects, and utilize information and physical evidence found at the scene (and, ultimately, analytical reports regarding that evidence) to locate, arrest and assist the prosecutor in bringing the alleged perpetrator before the courts.

Okay, now that we’ve got the characters straight, let’s take a closer look at the basic elements of CSI.


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