Case Planning and Scene Security: Pre-Investigation Protocol

Why Pre-Investigation Planning Matters

Walking onto a crime scene without a plan is one of the most dangerous and legally damaging mistakes a forensic technician can make. Contaminated evidence, injured personnel, and compromised court cases all trace back to poor scene management. The pre-investigation protocol — everything you do before a single item of evidence is touched — forms the foundation of every IAI CCSI domain and is directly tested on the certification exam. It also satisfies your legal obligations under federal OSHA standards, which apply to any employee who may contact blood or other potentially infectious materials (OPIM).

Hazard Assessment: Look Before You Touch

Your first responsibility at any scene is to recognize hazards. Use a systematic approach: scan from the outside in, from high to low, and from obvious to subtle.

Biological hazards include blood, body fluids, tissue, and any porous surface that may harbor pathogens. OSHA's Bloodborne Pathogen Standard (29 CFR 1910.1030) defines blood and OPIM and requires employers to provide exposure control plans, engineering controls, personal protective equipment, and training. As a technician, you must know this standard and apply it every time biological material is present or suspected.

Chemical hazards include clandestine drug labs, industrial solvents, agricultural pesticides, and unknown powders or liquids. The OSHA Hazard Communication Standard (29 CFR 1910.1200) requires chemical hazard information to be communicated through labels, Safety Data Sheets (SDS), and training. At a scene with suspected chemical hazards, do not enter until a qualified hazardous-materials team has assessed and, if necessary, mitigated the environment. Your scene management plan must document which standard applies to each identified hazard.

Physical hazards include unstable structures, sharp objects, electrical sources, fire risk, and traffic. Environmental hazards add weather, terrain, and water to the list.

Document every hazard in writing. An undocumented hazard is a liability for you, your agency, and the prosecution.

The Hierarchy of Controls and PPE Selection

OSHA's hierarchy of controls ranks hazard-reduction methods from most to least effective: elimination, substitution, engineering controls, administrative controls, and personal protective equipment (PPE). PPE is always the last line of defense, not the first solution.

For biological hazards at a typical homicide scene, minimum PPE includes nitrile examination gloves (double-gloved when risk is elevated), a fluid-resistant Tyvek suit or equivalent, shoe covers, eye protection, and a properly fitted N95 respirator or higher if aerosolization of blood is possible. For scenes with confirmed or suspected chemical hazards, you must defer to the hazmat team's guidance on respiratory protection level (A, B, C, or D) before entry.

Gloves must be inspected before donning and changed whenever they are torn, punctured, or heavily contaminated. Removing PPE (doffing) follows a strict sequence to prevent self-contamination: remove outer gloves first, then suit, then eye protection, then inner gloves, then mask — always moving from most contaminated to least contaminated.

Establishing the Perimeter

A crime scene perimeter has two concentric zones: the inner perimeter (the immediate area of the crime, where access is strictly limited to working personnel) and the outer perimeter (a buffer zone that keeps bystanders, media, and non-essential personnel away from the scene entirely).

When designing your perimeter, identify at least one primary entry/exit point and, when site geometry allows, a separate exit point for contaminated materials or personnel leaving the hot zone. Mark entry/exit points clearly on your perimeter diagram. The diagram should be drawn to an approximate scale, note cardinal directions, identify nearby structures and roads, and show the evidence search grid boundaries.

Once established, the perimeter must not move inward — it can only expand if new evidence or a wider area of disturbance is discovered. Shrinking a perimeter risks destroying evidence and can be challenged in court.

The Personnel Log

Every person who enters the inner perimeter must be recorded. A standard personnel log captures: full name, agency and title, date and time of entry, date and time of exit, purpose of entry, and the initials of the log keeper who verified the entry. This log becomes a legal document. In court, the defense will demand it to challenge chain of custody and scene integrity.

Designate one officer or technician as the log keeper at the entry point — that person does not leave the post or perform other tasks while on log duty.

Scene-Entry Priority List

Not everyone enters at once. Entry priority protects evidence and minimizes contamination. A standard priority sequence is:

1. Hazmat or medical personnel, if an active threat or injured person is present (life safety first)

2. The lead investigator or crime-scene supervisor, to conduct an initial walk-through and issue assignments

3. The photographer, to document the scene in its undisturbed condition before any collection begins

4. The sketch technician

5. Evidence collection personnel, working from the least disturbed areas toward the most disturbed

Support staff, supervisors making brief checks, and external specialists enter only with the lead investigator's authorization and are logged accordingly.

Connecting to IAI CCSI Requirements

The IAI CCSI exam tests scene management as a core domain. Candidates must demonstrate knowledge of perimeter establishment, personnel control, hazard recognition, and documentation. Your Scene Management Plan — the written deliverable for this lesson — mirrors exactly what the exam expects you to know. Every element in the 50-point rubric corresponds to a real-world scene-management responsibility and an exam content area. Treat this plan as both a class assignment and a study tool.