BSFS Crime Scene Investigation and Evidence Collection 2 — Questions and Answers
Question 1: Luminol is used at crime scenes to detect:
- Latent bloodstains that have been cleaned or are otherwise invisible (Correct answer)
- Gunshot residue on hands
- Trace fiber evidence on clothing
- Accelerant residue in fire debris
Correct answer: Latent bloodstains that have been cleaned or are otherwise invisible
Luminol reacts with the iron in hemoglobin to produce chemiluminescence, revealing bloodstains even after vigorous cleaning attempts.
Question 2: What type of evidence is a shoe print found in soft soil at a crime scene?
- Impression evidence (Correct answer)
- Trace evidence
- Pattern evidence
- Associative evidence
Correct answer: Impression evidence
Shoe prints, tire tracks, and tool marks in malleable surfaces are classified as impression evidence because they capture the three-dimensional form of the object.
Question 3: When collecting a wet blood sample from a crime scene for preservation, a forensic scientist should:
- Allow it to air dry completely before packaging in paper (Correct answer)
- Immediately seal it in a plastic zip-lock bag
- Mix it with a preservative on-site
- Freeze it in liquid nitrogen in the field
Correct answer: Allow it to air dry completely before packaging in paper
Wet blood must be air dried before paper packaging to prevent microbial growth and DNA degradation caused by trapped moisture.
Question 4: The 'primary crime scene' is defined as:
- The location where the crime actually occurred (Correct answer)
- The first location discovered by police
- Where the victim's body was found
- The scene with the most evidence
Correct answer: The location where the crime actually occurred
The primary crime scene is where the actual crime took place, which may differ from where a body or evidence is later found (secondary scene).
Question 5: Which technique is used to cast three-dimensional impressions (such as footwear or tire tracks) at a crime scene?
- Dental stone (plaster of Paris) casting (Correct answer)
- Superglue fuming
- Iodine fuming
- Magnetic powder dusting
Correct answer: Dental stone (plaster of Paris) casting
Dental stone is poured into the impression to create a durable three-dimensional cast that can be compared with known footwear or tires in the laboratory.
Question 6: A forensic investigator uses an alternate light source (ALS) at a crime scene primarily to:
- Visualize evidence that is not visible under normal white light, such as latent prints and biological fluids (Correct answer)
- Photograph evidence in high resolution
- Test surfaces chemically for blood
- Determine the age of fingerprints
Correct answer: Visualize evidence that is not visible under normal white light, such as latent prints and biological fluids
ALS emits specific wavelengths that cause certain substances to fluoresce or absorb light differently, making otherwise invisible evidence detectable.
BSFS Crime Scene Investigation and Evidence Collection 2
Luminol is used at crime scenes to detect: