Preserve an incident scene before ordinary operations erase the evidence

Source facts: initial responders protect life and control the scene

The U.S. Department of Justice’s Crime Scene Investigation: A Guide for Law Enforcement organizes scene work from initial response and prioritization through documentation, processing, completion, and evidence submission. Its initial-response principles put safety first, call for control of people and movement, and emphasize preventing contamination or loss while qualified investigators are summoned.

The guide describes scene boundaries, entry control, documentation of people and actions, witness management, and communication with investigative personnel. It recognizes that urgent medical aid and hazard control can change a scene; those changes should be limited to what is necessary and communicated. Protection of evidence begins before an evidence technician arrives.

The DOJ guide is intended for law enforcement. It does not grant private security personnel search, seizure, detention, evidence-collection, or investigative authority. Applicable law, property rights, employer policy, licensing, collective bargaining, insurer requirements, and law-enforcement direction govern a private organization. Security personnel should remain within training and authority.

DSE recommendation: stabilize, protect, record, and transfer

Write a first-arrival procedure for events that may become investigative scenes: assault, burglary, robbery, suspicious death or serious injury, major vandalism, forced door, weapon report, arson indication, or unexplained high-value loss. Give personnel a 24-hour escalation path and criteria for calling emergency services immediately.

Protect life and identify hazards. Call 911, provide aid within training, and address an active threat, fire, gas, electrical, structural, traffic, or environmental danger. Do not delay lifesaving action to preserve an object. Note what was moved, opened, shut down, cut, or removed and why.

Establish boundaries early. Begin wider than the obvious damage and adjust under authority. Use an inner boundary around the likely scene and an outer boundary for safe coordination, witnesses, media or public separation, and responder staging. Preserve entrance and exit paths for emergency personnel.

Control and log entry. Stop routine cleaning, repairs, deliveries, tours, and management walk-throughs. Record each person entering, time in and out, purpose, and authorizer. Essential fire, medical, utility, or safety work takes priority, but unnecessary observation does not.

Leave items and conditions alone. Do not pick up, unload, wipe, mark, smell, test, reassemble, search, or package an item unless immediate safety or authorized instruction requires it. Protect transient conditions such as weather exposure, footprints, tire marks, doors, lights, odors, temperature, or running equipment without contaminating them.

Identify people without conducting interrogations. Obtain names, safe contact information, location, and basic immediate observations. Keep witnesses from coordinating accounts when lawful and practical, provide care, and ask them to remain available for police. Record spontaneous statements accurately without leading questions.

Transfer deliberately. Brief the arriving authority on hazards, medical actions, boundaries, entries, changes, witnesses, available access records, and preserved systems. Confirm who controls the scene and who may authorize cleanup, repair, employee reentry, credential changes, or business reopening.

Secure relevant routine records against automatic loss under the approved legal process: access events, alarm logs, guard reports, visitor records, work orders, delivery records, and communications. Do not alter original records, create speculative annotations, or circulate sensitive material. Preserve integrity and document who collected each authorized copy.

Train with tabletop maps and ordinary props, never a surprise realistic crime scene. Test night shift, severe weather, injured persons, a manager demanding entry, essential equipment inside the boundary, and delayed police arrival. After release, photograph authorized conditions, retain the release record, complete repairs, support affected people, and review control failures. Good scene preservation is disciplined restraint: do what safety requires, keep others out, record what changed, and let the lawful investigator direct what comes next.

Official references

U.S. Department of Justice, Office of Justice Programs, Crime Scene Investigation: A Guide for Law Enforcement, September 2013.

National Institute of Justice, Crime Scene Investigation: A Guide for Law Enforcement, original technical working group guide.