CFE Crime Scene Investigation & Physical Evidence Processing — Questions and Answers
Question 1: When photographing a crime scene, the correct documentation sequence is:
- Close-up photographs first, then mid-range, then overall establishing shots
- Overall establishing shots first, then mid-range context photos, then close-up detail photographs (Correct answer)
- Mid-range photographs first to orient the scene, then overall, then close-up
- The sequence does not matter as long as all areas are photographed before evidence is moved
Correct answer: Overall establishing shots first, then mid-range context photos, then close-up detail photographs
The standard approach is to work from general to specific: overall shots establish the scene's spatial context, mid-range shots show relationships between evidence items, and close-up shots capture individual item detail. Reversing this order risks altering the scene before contextual documentation is complete.
Question 2: Locard's Exchange Principle, foundational to physical evidence forensics, states that:
- Every crime that occurs leaves a permanent digital trace
- Whenever two objects come into contact, there is always a transfer of material between them (Correct answer)
- Physical evidence must be corroborated by eyewitness testimony to be admissible
- The burden of proof rests with the party that controls access to the crime scene
Correct answer: Whenever two objects come into contact, there is always a transfer of material between them
Dr. Edmond Locard's principle holds that physical contact between a perpetrator and a scene or victim always results in a mutual transfer of trace materials (hair, fibers, soil, glass fragments, etc.). This underpins the entire logic of physical evidence collection — the perpetrator both leaves traces and takes traces away.
Question 3: Which type of physical evidence is MOST vulnerable to contamination and degradation if proper collection protocols are not followed?
- Documentary evidence such as paper records
- Tool mark impressions cast in dental stone
- Biological evidence such as blood, saliva, and touch DNA (Correct answer)
- Firearms and ballistic evidence
Correct answer: Biological evidence such as blood, saliva, and touch DNA
Biological evidence is highly susceptible to contamination from the examiner, environmental conditions (heat, humidity), cross-contamination between items, and DNA degradation from UV light or microbial activity. Strict collection protocols — gloves, separate packaging, refrigeration — are critical to maintain evidentiary value.
Question 4: The primary purpose of establishing a defined crime scene perimeter as the first responding action is to:
- Expedite evidence collection by focusing only on the most visible items first
- Provide an area for media to observe proceedings safely
- Prevent unauthorized access and protect the integrity of physical evidence from disturbance or contamination (Correct answer)
- Identify witnesses and separate them from each other for interviewing
Correct answer: Prevent unauthorized access and protect the integrity of physical evidence from disturbance or contamination
The moment a crime scene is disturbed — by responders, bystanders, or the environment — evidence may be destroyed or contaminated. Establishing a perimeter is the first protective action to preserve the scene in its original state before any systematic documentation or collection begins.
Question 5: When multiple items of physical evidence are collected from the same crime scene, each item should be:
- Placed together in a single container to maintain contextual relationships
- Packaged separately with individual labels documenting location, date, time, and collector (Correct answer)
- Handed directly to the lead investigator without packaging to speed processing
- Combined and logged as a single exhibit to simplify chain of custody documentation
Correct answer: Packaged separately with individual labels documenting location, date, time, and collector
Each item must be individually packaged and labeled to prevent cross-contamination between items and to maintain a clear, traceable chain of custody. Combining items in a single container can destroy trace evidence, introduce contaminants, and create evidentiary challenges that may render items inadmissible.
Question 6: A forensic examiner arrives at a scene where a deceased victim is present and there is a strong odor suggesting decomposition. The FIRST action the examiner should take is:
- Begin collecting biological evidence immediately to preserve DNA before further degradation
- Photograph the overall scene from the perimeter before donning any protective equipment
- Don appropriate personal protective equipment (PPE) before entering the scene (Correct answer)
- Notify the media of the biological hazard so they maintain a safe distance
Correct answer: Don appropriate personal protective equipment (PPE) before entering the scene
Personal safety is always the first priority. Biological hazards at decomposition scenes include pathogens, toxic gases, and biohazardous materials. No evidence collection activity should begin before the examiner is properly protected with appropriate PPE (gloves, respirator, Tyvek suit as needed) to prevent both self-contamination and scene contamination.
CFE Crime Scene Investigation & Physical Evidence Processing
When photographing a crime scene, the correct documentation sequence is: