Crime scene investigation (CSI) is a systematic, meticulous process where precision overrides speed. The entire objective is to recognize, preserve, and collect physical evidence to reconstruct a past event.
The protocol follows a strict sequence to ensure legal accountability and scientific integrity:
Establish Security: First responders immediately establish a perimeter using barrier tape. Controlling access prevents contamination from onlookers and essential personnel alike. Log books track everyone entering or exiting.
Documentation: Before anything is touched, investigators create a permanent record. They capture wide-angle, mid-range, and close-up photographs, compile detailed spatial sketches with precise measurements, and write descriptive notes.
Systematic Search: Investigators use structured patterns (like grid or spiral searches) to ensure no square inch is missed. They place yellow markers to identify potential evidence like latent prints, DNA, or ballistics.
Chain of Custody: Each item is individually packaged, sealed, and labeled. A meticulous paper trail records every single transfer of custody from the scene to the forensics lab. Any break in this chain can ruin the evidence's admissibility in court.
By treating the scene as a fragile, non-renewable resource, investigators ensure the physical facts speak clearly in the pursuit of justice.