Ch2. The Investigation Stage — Initiating and Conducting a Criminal Investigation

How Investigations Begin

Investigation Triggers:
Victim/witness report to police or prosecutor.
Law enforcement observation (patrol, surveillance).
Grand jury investigation (federal felonies).
Tip from confidential informant; anonymous tip.
Regulatory referral (SEC, IRS, etc.).

Victim Report:
Victim contacts law enforcement; officer takes
  complaint.
No right to compel prosecution; officer/prosecutor
  retains discretion.

Grand Jury Investigation:
Grand jury subpoena: compels documents or testimony.
Target, subject, and witness: different rights apply.
Target letter: informal notice that grand jury is
  investigating you; no constitutional right to appear.
Fifth Amendment: witness may invoke self-incrimination
  privilege; may be given immunity (28 U.S.C. § 6002 —
  use and derivative-use immunity).

Confidential Informants:
Used widely in drug, organized crime, terrorism cases.
Informant's reliability goes to probable cause analysis
  (Illinois v. Gates, 1983 — totality of circumstances).

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Consensual vs. Non-Consensual Investigation

Consensual (Voluntary) Investigation:
Voluntary interview: subject may refuse; no Miranda
  required unless in custody.
Consent search: voluntary consent = no warrant needed.
  Scope limited by consent given.
  Third-party consent: person with common authority
  may consent (United States v. Matlock, 1974).
  Limits: Georgia v. Randolph (2006) — physically
  present co-occupant's refusal overrides consent.

Non-Consensual (Compelled) Investigation:
Warrant-based: search warrant, arrest warrant.
Exceptions to warrant requirement (Ch3 detail):
  Search incident to arrest, plain view, exigent
  circumstances, automobile exception, inventory search.

Terry Stop (Investigative Detention):
Reasonable articulable suspicion — less than probable
  cause (Terry v. Ohio, 1968).
May briefly detain and frisk (pat-down for weapons).
Must be brief; cannot become a de facto arrest.

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Key Investigation Methods

Custodial Interrogation — Miranda Requirements:
Miranda v. Arizona (1966): before custodial
  interrogation, officer must warn:
  ① Right to remain silent.
  ② Statements may be used against you.
  ③ Right to attorney before and during questioning.
  ④ Right to appointed counsel if indigent.
"Custody": objective — would a reasonable person feel
  free to leave? (Howes v. Fields, 2012).
Invocation: unambiguous assertion of right.
Waiver: voluntary, knowing, intelligent (Berghuis v.
  Thompkins, 2010 — silence alone is not invocation).

Search and Seizure of Premises:
Warrant requirement: probable cause + particular
  description of place and items (4th Amendment).
Knock-and-announce rule: generally required unless
  officer has reasonable suspicion of danger (Wilson v.
  Arkansas, 1995).

Wiretapping and Electronic Surveillance:
Title III (18 U.S.C. §§ 2510–2522): judicial order
  required to intercept wire, oral, or electronic
  communications.
FISA (50 U.S.C. §§ 1801 et seq.): foreign intelligence
  surveillance; FISA Court authorization.

Digital Forensics:
Cell phone search: warrant required (Riley v. California,
  2014).
Cell-site location information: warrant required
  (Carpenter v. United States, 2018).
Cloud storage: Stored Communications Act (18 U.S.C.
  §§ 2701–2712) + 4th Amendment.

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Key Concept Cards

Miranda = Custody + Interrogation ★★★★★ : Miranda warnings are required only when two conditions are both met: (1) the suspect is in custody AND (2) the suspect is being interrogated. Memory tip: No custody = no Miranda; no interrogation = no Miranda.

Consent Search = No Warrant Needed ★★★★★ : Voluntary consent by a person with authority over the premises or object eliminates the warrant requirement. Scope of consent limits the search. Memory tip: Consent = voluntary waiver of 4th Amendment warrant requirement.

Terry Stop = Reasonable Suspicion ★★★★☆ : A Terry stop requires only reasonable articulable suspicion — significantly less than probable cause. It must be brief and limited in scope. Memory tip: Terry = RAS; arrest = PC; warrant = PC + particularity.

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Practice Quiz

Q. If a suspect remains silent during police questioning without invoking Miranda, can their silence be used against them?

Post-Miranda silence generally cannot be used as evidence of guilt after Miranda warnings are given. However, pre-arrest, pre-Miranda silence may be used against a suspect in some circumstances (Salinas v. Texas, 2013 — a plurality held that selective pre-arrest silence can be used for impeachment if Miranda was not invoked). The safest approach for a suspect is an unambiguous verbal invocation: “I am invoking my right to remain silent” or “I want a lawyer.” Merely staying quiet is not an invocation under Berghuis v. Thompkins (2010).

Q. What are the constitutional requirements for a warrantless arrest in a public place?

A warrantless arrest in a public place is constitutional if the officer has probable cause to believe the person committed a crime (United States v. Watson, 1976). Probable cause means a fair probability or substantial chance — more than a hunch, but less than a preponderance. For arrest inside a home, an arrest warrant is required absent exigent circumstances (Payton v. New York, 1980). After arrest, the suspect must be brought before a magistrate for a probable-cause determination within 48 hours (Riverside County v. McLaughlin, 1991).