CSI Impression and Pattern Evidence 2 — Questions and Answers
Question 1: When casting a tire track impression in soft soil, what material is most commonly used?
- Plaster of Paris
- Dental stone (Correct answer)
- Silicone rubber
- Epoxy resin
Correct answer: Dental stone
Dental stone is preferred over plaster of Paris because it is harder, more durable, and captures finer detail.
Question 2: What is the primary purpose of electrostatic lifting in footwear examination?
- Recovering latent fingerprints from shoe soles
- Lifting dry, dusty shoe impressions from hard surfaces (Correct answer)
- Removing shoe impressions from carpet fibers
- Chemically enhancing bloody shoe prints
Correct answer: Lifting dry, dusty shoe impressions from hard surfaces
An electrostatic lifting device (ESDA) uses static charge to transfer dry dust impressions onto a black lifting film.
Question 3: A bite mark on a victim's skin shows individual tooth characteristics. Which characteristic is NOT typically used in bite mark analysis?
- Tooth size and shape
- Spacing between teeth
- Dental enamel color (Correct answer)
- Rotation of individual teeth
Correct answer: Dental enamel color
Enamel color is not a reliable or useful characteristic in bite mark comparison because skin impressions do not record color.
Question 4: In tire track analysis, what does 'track width' refer to?
- The width of a single tire tread
- The distance between the left and right tires on the same axle (Correct answer)
- The length of the tire contact patch
- The depth of the tire groove
Correct answer: The distance between the left and right tires on the same axle
Track width is measured from the center of the left tire to the center of the right tire on the same axle, helping narrow down vehicle type.
Question 5: When photographing a shoe impression in soil at a crime scene, what is the correct oblique lighting angle?
- 90 degrees (directly overhead)
- 45 degrees
- A low angle of approximately 10-45 degrees (Correct answer)
- Any angle is equally effective
Correct answer: A low angle of approximately 10-45 degrees
Low oblique lighting at 10–45 degrees casts shadows that highlight the three-dimensional detail of the impression.
Question 6: What is a 'Wheelbase' measurement in tire track evidence?
- The circumference of one tire
- The distance from the front axle to the rear axle (Correct answer)
- The number of grooves in a tread pattern
- The sidewall height of a tire
Correct answer: The distance from the front axle to the rear axle
Wheelbase is the distance between the front and rear axles and can help classify the type and make of a vehicle.
Question 7: Which type of shoe print would be classified as a 'patent impression'?
- A print visible only under UV light
- A print made in soft mud requiring casting
- A visible print left in blood or paint on a hard floor (Correct answer)
- A latent print revealed by fingerprint powder
Correct answer: A visible print left in blood or paint on a hard floor
A patent impression is already visible to the naked eye, such as a bloody or muddy shoe print left on a hard surface.
CSI Impression and Pattern Evidence 2
When casting a tire track impression in soft soil, what material is most commonly used?