CPD Investigation & Evidence 5 — Questions and Answers
Question 1: What is the correct order of steps when collecting physical evidence at a crime scene?
- Document, photograph, collect, package, and label (Correct answer)
- Collect, photograph, document, package, and label
- Photograph, collect, document, label, and package
- Label, document, photograph, collect, and package
Correct answer: Document, photograph, collect, package, and label
Proper evidence handling requires documentation and photography before any item is collected, then packaging and labeling for chain of custody.
Question 2: A confidential informant provides a tip that a specific apartment contains illegal weapons. To obtain a search warrant, the officer must demonstrate:
- The informant's reliability and basis of knowledge, establishing probable cause (Correct answer)
- That the informant has testified in court before
- That the weapons have been seen by at least two officers
- Only that the informant has a criminal record
Correct answer: The informant's reliability and basis of knowledge, establishing probable cause
Under the Illinois v. Gates totality-of-circumstances test, the informant's track record and how they know what they claim to know must support probable cause.
Question 3: Which interview technique involves allowing a witness to narrate events in their own words without interruption before asking clarifying questions?
- Cognitive interview technique (Correct answer)
- Reid technique
- PEACE model structured questioning
- Leading question methodology
Correct answer: Cognitive interview technique
The cognitive interview encourages free recall narrative first, which produces more accurate and complete information from witnesses.
Question 4: A suspect is arrested and invokes their right to counsel. Investigators must:
- Immediately cease questioning and not resume until counsel is present (Correct answer)
- Allow a brief 15-minute cooling-off period then resume questioning
- Contact the public defender's office and continue questioning in the interim
- Limit questions to administrative matters like name and address
Correct answer: Immediately cease questioning and not resume until counsel is present
Invoking the right to counsel requires all questioning to stop until an attorney is present, per Edwards v. Arizona.
Question 5: Trace evidence such as hair, fiber, and glass fragments is governed by Locard's Exchange Principle, which states:
- Every contact between a person and a place leaves a mutual transfer of material (Correct answer)
- All physical evidence eventually degrades and becomes unreliable
- Officers must not disturb trace evidence under any circumstances
- Trace evidence requires court approval before laboratory testing
Correct answer: Every contact between a person and a place leaves a mutual transfer of material
Locard's principle holds that whenever two objects come into contact, they exchange material, making trace evidence forensically valuable.
Question 6: An officer prepares a case report for a robbery investigation. The report should contain:
- Factual observations, witness statements, evidence collected, and all investigative steps taken (Correct answer)
- The officer's opinion about who committed the crime
- Only information favorable to the prosecution
- A prediction of the likely sentence if convicted
Correct answer: Factual observations, witness statements, evidence collected, and all investigative steps taken
Investigative reports must be objective, factual, and comprehensive, documenting all observations and actions without editorial opinion.
Question 7: Under Illinois law, how long may police generally detain a suspect for investigation before charges must be filed or the suspect released?
- 48 hours, with judicial approval required to extend detention (Correct answer)
- 24 hours without any judicial review
- 72 hours as a general rule for all offenses
- Until the investigating detective completes their report
Correct answer: 48 hours, with judicial approval required to extend detention
Illinois law generally requires that a detainee be brought before a judge within 48 hours; detention beyond that requires judicial authorization.
CPD Investigation & Evidence 5
What is the correct order of steps when collecting physical evidence at a crime scene?