Investigations and Evidence Handling
What the exam tests
This domain tests whether you can manage a case from first response to charging: evidence integrity, chain of custody, interviews, lineups, search warrants, and Brady disclosure.
Core rules
- Chain of custody: every transfer is documented with date, time, handler, and purpose.
- Package biological evidence to dry; do not seal wet blood or tissue in plastic.
- Digital evidence: preserve the original, hash it, document extraction, and maintain an audit trail.
- Non-custodial interviews do not require Miranda; custodial interrogation does.
- Photo lineups use double-blind administration, unbiased fillers, and documented instructions.
- Warrant affidavits state facts, not conclusions, and omit nothing that undermines probable cause.
- Brady and Giglio require disclosure of exculpatory and impeachment information.
Worked example
A sergeant reviews a burglary file. The officer collected a bloody glove in a plastic bag and left it in a hot car for two days. The sergeant should document the storage problem, notify the evidence technician and prosecutor, preserve the item as-is, and consider whether it still has probative value. Reasoning: the sergeant cannot undo contamination, but can prevent concealment and let the lab and prosecutor assess admissibility. Hiding the issue would damage the case and credibility.
Traps that cost marks
- Breaking the chain by signing for evidence you did not handle.
- Packaging wet evidence in plastic.
- Writing warrant affidavits with conclusions and no facts.
- Failing to document witness interviews or lineup procedures.