The job description of a crime scene investigator is a rather complex and multi-faceted one, as a number of subspecialties exists within this profession. However, in general, a crime scene investigator is a professional who is trained to collect, preserve and process evidence at the scene of a crime.
Crime scene investigators, unlike forensic scientists who conduct tests on physical evidence within a forensic laboratory, are the on-the-scene professionals who are called to the scene of a crime to ensure that all physical evidence is properly collected, preserved and documented according to a strict code of standards. These investigative professionals also ensure that all physical evidence is packaged and transported to a forensic laboratory.
A crime scene investigator, at the scene of a crime, may:
- Work with law enforcement to identify, isolate and secure the crime scene
- Work with law enforcement to establish a restricted perimeter around the crime scene as to not compromise evidence
- Work with law enforcement to define a clear set of restrictions regarding nonessential personnel and investigative personnel
- Preserve, collect and record impressions, including toolmarks, footprints, tire marks, bite marks, and fingerprints
- Collect DNA evidence, including blood, semen, hair, skin, blood stain patterns, bodily fluids and nails
- Collect trace evidence, including gunshot residue, fibers, accelerant, paint, glass, etc.
- Collect firearms evidence, including weapons, spent casings, bullet fragments, cartridges, and gun powder patterns
Throughout a crime scene investigation, CSI professionals must ensure that:
- All laws are followed
- The crime scene and all collected evidence are properly documented
- Evidence is processed in an expeditious manner
- Evidence is processed without compromising it
- Proper methods and techniques for evidence recovery are followed
- All equipment and resources are properly used
- All evidence is properly handled, packaged and transported
- All physical evidence is recovered
- Safety precautions are followed
The Crime Scene Approach
Regardless of the specific job of the crime scene investigator, all CSI professionals at the scene of a crime must adhere to the same set of regulations and the same protocol, which generally includes:
- Scene Recognition
The initial phase of a crime scene investigation involves identifying and recognizing the scene and the physical evidence to be collected. A crime scene leader is generally responsible for this initial, organizational phase, which involves approaching the search using an organized method or pattern. This may mean identifying the number of CSI professionals on the scene, the size of the area, and the extent of the crime scene. Recognizing the scene and the physical evidence at the scene is crucial as to ensure that the evidence is not compromised in any way and that it can be identified, processed, and packaged in an organized fashion. This phase of the investigation also involves identifying the resources and equipment that may be needed and identifying and addressing any safety concerns or hazards.
- Scene Documentation
The next phase involves documenting and processing the physical evidence. This is done through written notes, diagrams, reports, photographs, and sketches. This information must be comprehensive, accurate, and factual, as it may be used by forensic scientists in the laboratory, by law enforcement officials, and in a court of law.
- Evidence Collection
Once the crime scene has been properly assessed and all information has been recorded, it is the job of the crime scene investigators to recover the physical evidence at the crime scene through a number of technical and scientific methods and procedures. Proper care must be taken at all times to ensure that the physical evidence is collected and preserved according to strict standards.
Education and Training
The majority of CSI job descriptions involve specific education and training requirements.
It is up to crime scene investigators, regardless of their title, specialty, or professional scope, to ensure that a step-by-step approach to identifying, collecting and preserving physical evidence is achieved. Therefore, crime scene investigators are educated and trained investigative professionals who are well versed in the law, the criminal justice system and, of course, the documentation and recovery of physical evidence. Four-year degrees in this field are commonplace, with employers often demanding that candidates have a comprehensive education in criminal justice, forensic science, or a similar program. A clearly defined probationary period during which extensive, on-the-job training takes place, is also common in this profession.
Post-graduate work and master’s programs are also often pursued by crime scene investigators as to achieve CSI jobs that require specialized knowledge, such as DNA, latent print, and firearms, for example.
Job descriptions for crime scene investigators may vary according to the geographic location, the size of the law enforcement agency, or simply the size and scope of the crime scene. Within larger cities, for example, crime scene investigators may be hired to perform specific duties, such as DNA or fingerprint collection, while smaller locations may require crime scene investigators to tackle any number of tasks at a crime scene.