CSI Impression and Pattern Evidence 3 — Questions and Answers
Question 1: What does 'class characteristics' mean in the context of shoe print evidence?
- Unique wear patterns specific to one individual's shoe
- General features shared by all shoes of the same make, model, and size (Correct answer)
- Characteristics created by post-manufacture damage
- Microscopic fiber transfers on the shoe sole
Correct answer: General features shared by all shoes of the same make, model, and size
Class characteristics identify a shoe as belonging to a particular design group but do not distinguish one specific shoe from another of the same type.
Question 2: A CSI finds a patterned tool mark on a door frame where a screwdriver was used to pry it open. What type of mark is this?
- Striated mark (Correct answer)
- Compression mark
- Abrasion mark
- Impressed mark
Correct answer: Striated mark
A striated (or striations) mark is produced when a tool slides across a surface, leaving parallel scratch marks unique to that tool's edge.
Question 3: In blood spatter analysis, what does a 'satellite spatter' indicate?
- Blood that traveled a long distance before landing
- Small secondary droplets that break away when a primary drop strikes a surface (Correct answer)
- Spatter created by a medium-velocity impact
- Blood that was projected from an arterial wound
Correct answer: Small secondary droplets that break away when a primary drop strikes a surface
Satellite spatters are tiny droplets that radiate outward from the primary bloodstain upon impact, caused by the energy of the falling drop.
Question 4: When collecting a casting from a shoe impression in snow, which method helps prevent the cast from melting the impression?
- Pouring boiling water into the casting material
- Using Snow Print Wax spray as a protective layer before casting (Correct answer)
- Mixing dental stone with hot water
- Applying chemical fixative directly to the snow
Correct answer: Using Snow Print Wax spray as a protective layer before casting
Snow Print Wax is sprayed into the impression to create a barrier that prevents the exothermic reaction of dental stone from melting the snow detail.
Question 5: What is the significance of a 'void pattern' in blood spatter evidence?
- It shows the trajectory of a projectile through air
- It indicates an area where blood was absent because an object blocked the spatter (Correct answer)
- It represents blood wiped away by a cloth
- It identifies the direction of an arterial spurt
Correct answer: It indicates an area where blood was absent because an object blocked the spatter
A void pattern is a blank area within a blood spatter distribution, indicating that an object or person was present and blocked blood from reaching that area.
Question 6: In tool mark analysis, what process is used to create a comparison standard from a suspected tool?
- Photographing the tool under UV light
- Making test marks on the same type of material found at the crime scene (Correct answer)
- Running the tool through an AFIS database
- Chemically etching the tool blade for examination
Correct answer: Making test marks on the same type of material found at the crime scene
Examiners create test marks using the suspected tool on similar material to compare the unique striations against the crime scene mark.
Question 7: What does 'directionality' indicate in the study of blood spatter?
- The type of weapon used to cause the wound
- The direction from which a blood droplet traveled before it struck a surface (Correct answer)
- The volume of blood lost by the victim
- The time elapsed since the bloodshed occurred
Correct answer: The direction from which a blood droplet traveled before it struck a surface
Directionality is determined by the shape of the bloodstain — an elliptical stain points toward the direction of travel, with the tail or satellite droplets on the downrange side.
CSI Impression and Pattern Evidence 3
What does 'class characteristics' mean in the context of shoe print evidence?