Investigations and Evidence Handling
Build the case so it survives a suppression hearing
Investigations are graded on two things: whether the evidence is admissible and whether it can be authenticated. Begin with a written plan of what is alleged, what is known, and what facts are still needed, then document chronologically in observable terms. Reports must separate what you saw and heard from what witnesses concluded and from what you inferred; that separation is what lets a prosecutor defend your affidavit.
Evidence handling: photograph before you move anything, collect with gloves, package items separately, and label date, time, location, collector, and case number. Keep the chain of custody unbroken and documented at every transfer. Biological evidence air-dries; never seal wet items in plastic. Drug evidence is field-tested, weighed, and submitted under the Controlled Substance, Drug, Device and Cosmetic Act (35 P.S. § 780-101 et seq.), with a property receipt copy to the defendant.
Search warrants: the affidavit is judged on its four corners, so every fact supporting probable cause must appear in it, including staleness, informant reliability, and basis of knowledge. The warrant must particularly describe the place and the items. Material omissions or misstatements made knowingly or recklessly can void it (Franks v. Delaware). Consent searches require voluntariness, authority over the area, and staying inside the scope granted; consent can be withdrawn.
Identification procedures are a common weakness: use a blind or blinded administrator, avoid suggestiveness in arrays, and record the witness's own words and confidence statement before any feedback.
Traps: testifying that a substance was narcotics as a conclusion rather than a test result; gaps in chain of custody; paraphrasing a witness instead of quoting. Rule of thumb: if you cannot point to the line in the affidavit or the custody form that proves it, assume the defense will find that gap.