Securing the Scene
The first officer at a crime scene has two priorities: ensure safety and protect the scene. After confirming no threats remain and providing medical aid to victims, the officer establishes a perimeter using barrier tape, restricting access to authorized personnel only. A crime scene log records every person who enters and exits, with times. Contamination—the introduction of extraneous material that could compromise evidence—is the greatest enemy of crime scene processing. Officers must avoid touching surfaces, walking through blood, or moving objects. A common mistake is allowing too many people into the scene; studies show that each additional person increases the risk of contamination and evidence destruction. Only essential personnel—the lead investigator, crime scene technicians, photographer, and medical examiner—should enter.