FDLE Criminal Investigation Procedures 2 — Questions and Answers
Question 1: What is the primary purpose of establishing a perimeter at a crime scene?
- To enable media access to document the scene
- To protect the integrity of evidence and control access (Correct answer)
- To allow rapid evidence collection before the scene is contaminated
- To ensure witness interviews can occur near the scene
Correct answer: To protect the integrity of evidence and control access
Establishing a perimeter at a crime scene is essential to protect evidence integrity and control who enters the scene, preventing contamination or alteration of physical evidence.
One of the first actions at any crime scene is establishing inner and outer perimeters. The inner perimeter encompasses the crime scene itself and is restricted to essential personnel only. The outer perimeter provides a buffer for staging, command, and witness interviews. The purpose: preserve evidence in its original state, prevent contamination, maintain chain of custody, protect officer safety, and control media and bystanders. Florida CJSTC training emphasizes that the first officer on scene is responsible for securing and protecting the scene until investigators arrive.
Question 2: In a criminal investigation, what does 'chain of custody' refer to?
- The hierarchy of command during a major investigation
- The documented chronological record of who collected, handled, and stored evidence (Correct answer)
- The sequence of arrests made in a criminal conspiracy case
- The order in which witnesses are interviewed
Correct answer: The documented chronological record of who collected, handled, and stored evidence
Chain of custody is the documented, unbroken record tracking who collected, transferred, analyzed, and stored each piece of evidence from discovery to court presentation.
Chain of custody documents the seizure, custody, control, transfer, analysis, and disposition of physical and electronic evidence. A complete chain must show: who collected the evidence, where and when, who took possession, how it was stored, who had access, and every transfer of possession. Breaks in the chain can result in evidence being challenged or excluded at trial. Florida law enforcement agencies maintain evidence logs, use numbered tamper-evident packaging, and require documented transfers.
Question 3: Which type of crime scene sketch provides the most accurate representation of measurements and spatial relationships?
- Rough sketch
- Finished/formal sketch drawn to scale (Correct answer)
- Overhead bird's-eye view sketch without measurements
- Perspective sketch
Correct answer: Finished/formal sketch drawn to scale
A finished sketch drawn to scale provides the most accurate representation because it maintains proportional measurements, making it admissible and useful for courtroom presentation.
Crime scene sketches serve as permanent records of the scene. Two main types: the rough sketch (made at the scene, not to scale, working document) and the finished/formal sketch (drawn to scale using measurements from the rough sketch, used in court). A to-scale sketch maintains proportional accuracy — every measurement is reduced by the same factor, allowing accurate reconstruction of distances and spatial relationships. The finished to-scale sketch is the evidentiary standard.
Question 4: What is the recommended method for processing a crime scene when its boundaries and significant items are unknown?
- Random collection of visible items
- Systematic search method (grid, zone, or spiral) (Correct answer)
- Selective collection of only visible items
- Photographing only, without physical collection
Correct answer: Systematic search method (grid, zone, or spiral)
Systematic search methods — such as grid, zone, spiral, or strip patterns — ensure complete coverage of an unknown crime scene without missing evidence.
Florida CJSTC training covers multiple systematic crime scene search patterns: Strip/Lane method — officers walk parallel paths, Grid method — two overlapping strip searches at right angles (most thorough), Zone/Sector method — scene divided into sections, Spiral method — inward or outward spiral useful for outdoor scenes. The method selected depends on scene size, terrain, and available personnel. Systematic methods prevent tunnel vision and ensure all areas are searched.
Question 5: When interviewing a witness to a crime, which technique is most effective for obtaining accurate, complete information?
- Asking leading questions to confirm the officer's theory
- Cognitive interview technique using open-ended questions (Correct answer)
- Rapid-fire closed questions to obtain facts quickly
- Presenting the witness with a list of possible answers
Correct answer: Cognitive interview technique using open-ended questions
The cognitive interview technique, which uses open-ended questions and memory-enhancing strategies, is the most effective and scientifically validated method for obtaining accurate witness recall.
The Cognitive Interview (CI), developed by Fisher and Geiselman, uses: mental reinstatement of context, reporting everything, recalling events in different orders, and changing perspectives. Florida CJSTC training emphasizes open-ended, non-leading questions to avoid contaminating witness memory. Leading questions can implant false details and compromise the reliability of eyewitness testimony.
Question 6: What is the significance of 'Locard's Exchange Principle' in criminal investigations?
- Every crime has a motive that can be identified through evidence
- Every contact leaves a trace — perpetrators bring something to and take something from every crime scene (Correct answer)
- Physical evidence is always more reliable than eyewitness testimony
- Crime scenes must be sealed within one hour of discovery
Correct answer: Every contact leaves a trace — perpetrators bring something to and take something from every crime scene
Locard's Exchange Principle states that every contact between two objects results in an exchange of material — the criminal always leaves traces at the scene and takes traces away.
Dr. Edmond Locard (1877–1966) formulated: 'Every contact leaves a trace.' When a perpetrator enters a crime scene, they leave physical evidence (fingerprints, hair, fibers, biological material) and take evidence away (trace fibers, soil, victim's DNA). This principle underlies all forensic science. It means no crime can be committed without the criminal leaving some evidence — the investigator's job is to find and preserve it.
FDLE Criminal Investigation Procedures 2
What is the primary purpose of establishing a perimeter at a crime scene?