Criminal Investigation Procedures Flashcards

When processing a crime scene, what is the primary purpose of establishing a perimeter?

Answer: To preserve evidence integrity and prevent contamination

A crime scene perimeter is established to protect evidence from contamination, unauthorized access, and disturbance.

A witness recants their statement after initially identifying a suspect. What should the investigator do first?

Answer: Document the recantation and investigate the reason for the change

Investigators must document recantations and probe the reasons, as witnesses may recant due to fear, coercion, or new information.

Under Virginia law, which standard must be met before an officer can conduct a Terry stop?

Answer: Reasonable articulable suspicion

A Terry stop requires reasonable articulable suspicion of criminal activity, a lower standard than probable cause.

What is 'chain of custody' in the context of criminal investigation?

Answer: A chronological documentation of evidence handling from collection to court

Chain of custody is the documented record of every person who handled evidence and every location it was stored, ensuring admissibility.

When interviewing a juvenile suspect in Virginia, what additional requirement typically applies?

Answer: A parent, guardian, or attorney must generally be notified or present

Virginia law provides heightened protections for juvenile suspects, generally requiring notification of a parent, guardian, or legal counsel.

What is the purpose of photographing a crime scene before collecting evidence?

Answer: To create a permanent record of the original scene conditions

Pre-collection photography preserves the original state of the scene, which is critical for court presentation and investigation review.

Which type of lineup procedure is generally considered most reliable for eyewitness identification?

Answer: Sequential lineup administered by a blind administrator

Sequential lineups administered by someone unaware of the suspect's identity reduce suggestibility and relative judgments by witnesses.

What does 'exculpatory evidence' mean in a criminal investigation?

Answer: Evidence that tends to clear or excuse a suspect from guilt

Exculpatory evidence tends to negate a defendant's guilt and must be disclosed to the defense under Brady v. Maryland.

An officer discovers a body and suspects homicide. What should be the first investigative priority?

Answer: Secure and protect the scene before any evidence is touched

Scene security is always the first priority in a homicide investigation to prevent evidence loss or contamination.

In Virginia, a consent search requires that consent be:

Answer: Voluntary and not the product of coercion or duress

Valid consent must be freely and voluntarily given; consent obtained through threats, coercion, or deception is constitutionally invalid.

What is a 'modus operandi' (MO) and why is it important in investigations?

Answer: A suspect's characteristic method of committing crimes, useful for linking cases

MO refers to a criminal's signature methods and habits, which investigators use to connect multiple crimes to a single offender.

When is it appropriate for an investigator to use a ruse or deception during a suspect interview?

Answer: Before Miranda warnings are given, within legal limits

Courts have allowed certain deceptive interview tactics before Miranda warnings, but deception cannot be used to overbear the suspect's will.

What is the significance of 'Locard's Exchange Principle' in criminal investigations?

Answer: Any contact between persons or objects results in an exchange of trace materials

Locard's Exchange Principle holds that every contact leaves a trace, forming the scientific foundation for trace evidence collection.

An officer responding to a burglary finds the door ajar and hears movement inside. What doctrine may justify immediate warrantless entry?

Answer: Exigent circumstances

Exigent circumstances allow warrantless entry when there is an urgent need to prevent imminent danger, destruction of evidence, or escape of a suspect.

During a traffic stop, an officer smells marijuana emanating from the vehicle. Under current Virginia law, how does this affect the search?

Answer: Odor alone may not be sufficient probable cause given marijuana's legal status in Virginia

Since Virginia legalized marijuana possession for adults, courts have held that odor alone may no longer establish probable cause to search a vehicle.

What is a 'victimology' analysis in a homicide investigation?

Answer: A thorough study of the victim's background, lifestyle, and relationships to identify suspects

Victimology examines who the victim was, their routines, and relationships to understand why they were targeted and narrow the suspect pool.

Which rule governs when physical evidence obtained in violation of the Fourth Amendment may be excluded from trial?

Answer: The Exclusionary Rule

The Exclusionary Rule bars the use of evidence obtained through unconstitutional searches and seizures, with the Fruit of the Poisonous Tree doctrine extending this to derivative evidence.

An investigator is conducting surveillance. At what point does surveillance become constitutionally significant?

Answer: When it reveals information the subject had a reasonable expectation of privacy in

Surveillance implicates the Fourth Amendment when it intrudes on areas or information where a person has a reasonable expectation of privacy.

What is the purpose of a 'case file' or investigative folder maintained throughout a criminal investigation?

Answer: To organize all documentation, evidence records, and investigative steps for court preparation and review

A complete case file documents every step of the investigation, ensuring accountability, continuity, and providing prosecutors the materials needed for prosecution.

What is the difference between a 'field identification' (showup) and a formal photo array?

Answer: A showup is an immediate on-scene one-person identification; a photo array presents multiple photos later

A showup is a prompt one-on-one identification near the crime scene, while a photo array is a structured multi-photo identification procedure conducted later.