Investigations, Evidence, and Case Preparation
What this domain tests
Investigations, Evidence, and Case Preparation tests your ability to build a case that survives suppression and trial: lawful searches, reliable identification, preserved evidence, complete reports, and disclosure of exculpatory material.
Core rules
- A search warrant affidavit must establish probable cause and describe with particularity the place to be searched and items to be seized. Massachusetts does not excuse a defective warrant on good-faith grounds.
- Chain of custody must show each transfer of evidence, who handled it, when, and where; gaps create suppression and credibility problems.
- Eyewitness identification should use a blind or blinded procedure, sequential presentation, unbiased instructions, and a confidence statement in the witness's own words.
- In sexual assault cases, the first complaint doctrine limits proof of complaint; identify the first complaint witness and do not create a later complaint for convenience.
- Case preparation means matching every element to evidence, anticipating defenses, and disclosing Brady material.
- Digital evidence needs hash values, device details, and a documented extraction process.
Worked example
A convenience store is robbed at gunpoint. The officer preserves CCTV, collects the demand note with gloves, and packages the firearm separately. The witness views a sequential photo array administered by an officer not involved in the case, signs a confidence statement, and identifies the suspect. The report lists each element (taking, force or threat, firearm) and the evidence supporting it. The chain of custody for the note and gun is documented from scene to lab.
Traps
Filling chain-of-custody gaps with assumption; using a showup without justification; paraphrasing witness words; withholding inconsistent witness statements; and listing evidence without linking it to an element.