Unit 7 Flashcards
(28 cards)
What are the tool mark categories?
compression, striation, cutting.
What factors contribute to tools’ unique characteristics?
Factors include wear, damage, manufacturing variations, and the specific use of the tool.
What is casting? When is the process pursued?
Casting is the process of creating a replica of a tool mark or impression using materials like plaster or silicone. It is typically pursued when the original mark needs to be preserved or if it is in a fragile or difficult-to-examine state.
How do indentation marks, cutting marks, and abrasion marks vary?
- Indentation marks are caused by the force of a tool pressing into a softer surface.
- Cutting marks are made by a sharp edge slicing through material.
- Abrasion marks are produced when a surface is worn down by friction with a tool.
What types of marks are created by various types of saws?
Saws can create cutting marks (from teeth) and abrasion marks (from the blade’s edge).
What are the three categories of impressions?
The three categories of impressions are latent impressions, patent impressions, and plastic impressions.
How is impression evidence typically collected and/or documented?
Impression evidence is typically photographed and cast using materials like plaster, or documented by lifting with adhesive or tape.
What might tool mark evidence reveal to investigators? What can it not reveal?
Tool mark evidence can link a tool to a crime scene or victim. It cannot reveal the specific person who used the tool.
What methods are used to make latent prints visible?
Methods include dusting with powders, using chemical reagents, or applying UV light.
What types of tire patterns do motor vehicles typically leave?
tracks and tread
tracks show width, length, direction
tread show brand/type
What components combine to create a tire’s tread surface?
The tire tread is created by the rubber compound, tread blocks, and grooves designed for traction.
What is a track width? How is it calculated?
Track width is the distance between the centers of the left and right tires on a vehicle. It is calculated by measuring the width of the tire tracks left by the vehicle.
What is a wheelbase? How is it calculated?
Wheelbase is the distance between the front and rear axles of a vehicle. It is calculated by measuring from the center of the front axle to the center of the rear axle.
How do a tire’s ridges and grooves differ? Why are they each important in investigation?
Ridges are raised parts, and grooves are indented. Both are unique to a tire and can be used to identify the make, model, and condition of the vehicle.
How do investigators use tracks to determine a vehicle’s wheelbase?
By measuring the distance between corresponding points of tracks left by the front and rear tires, investigators can estimate the wheelbase.
What might tire evidence reveal to investigators? What can it not reveal?
Tire evidence can reveal the make, model, and possibly the year of a vehicle. It cannot identify the driver of the vehicle.
What are the different ways to obtain and record footwear evidence?
Footwear evidence can be obtained by photographing, casting, or using lifting techniques to collect prints or impressions.
How are a person’s height and shoe size related, if at all? If they’re related, how might that be calculated?
Height and shoe size are loosely correlated, but not precisely. Estimation formulas may give an approximation based on shoe size.
How might one determine a person’s stride length?
Stride length can be measured by observing and measuring the distance a person covers in a single stride or by using a mathematical formula based on height.
What is individual evidence? What might footwear evidence reveal to investigators? What can it not reveal?
Individual evidence links a suspect to a specific crime scene. Footwear evidence can reveal the type, size, and possibly the unique wear patterns of a shoe but cannot identify the individual who wore the shoe.
What might bite mark evidence reveal to investigators? What can it not reveal?
Bite mark evidence can reveal the size, shape, and possibly the identity of the person who made the mark. It cannot reveal the full identity of the individual or other personal details.
What are the symbols used to characterize bite marks?
Bite marks can be described using symbols that represent the size, shape, and pattern of the marks, such as linear, circular, or irregular.
How is bite mark evidence classified?
usually class evidence
What particular teeth’s measurements are typically measured and compared in bite mark analysis?
Measurements of the upper and lower incisors, canines, and molars are typically compared in bite mark analysis.
