Incident Investigation 3: Scene Management, Evidence and Witness Interviewing
Scope of this domain
Domain 3 tests evidence handling: securing the scene, gathering documentary and physical evidence, and interviewing witnesses without contaminating their account.
Core rules
- Three evidence families: people (injured person, witnesses, supervisors), paperwork (risk assessments, permits, training and maintenance records, CCTV, telemetry) and physical/position (damage, positions, measurements, photographs, sketches, samples).
- Preserve the scene: make safe, cordon it, record before moving anything, keep a chain of custody for items removed.
- Interview witnesses as soon as practicable, separately, in a neutral private place; explain the purpose, who will see the record and how confidentiality is handled.
- Use a question funnel: open ("tell me what you saw"), then probing, then closed confirmation. Avoid leading, multiple, hypothetical and judgemental questions; cognitive-interview prompts (reinstating context, recalling from another viewpoint) improve recall.
- Record notes contemporaneously; have statements read, corrected and signed. Separate observation from opinion.
- Corroborate every account against documents and physical evidence before relying on it.
Worked example
A witness says "the forklift was going too fast". That is an opinion. Convert it to fact: where were you standing, what did you actually see, roughly how far away was the truck, what load was it carrying, did you hear the horn? Then check tachograph or fleet telemetry and CCTV for speed and route.
Traps
Interviewing witnesses together; leading questions that plant detail; writing notes hours later; ignoring the injured person when they are able to contribute; preferring the most confident witness over documentary evidence.