Forensics Chapter 16 Shoe and Tire Impression Quiz Objectives

Patent impressions

Visible when an object picks up soil, dust, paint, blood, or other material and transfers it elsewhere (2D transfer)

Latent impressions

Prints hidden/invisible to the unaided eye but can be made visible (lifted) through the use of special dusting and electrostatic techniques

Plastic impressions

Prints that can be left in soft materials, such as snow, mud, soil, etc

Class evidence

Is the sole and tread of a shoe part of class evidence or individual evidence?

Individual evidence

Is gait and tracks part of class evidence or individual evidence?

Sole

Bottom of a piece of footwear

Tread

The part of a tire that meets the road: the pattern on the sole of footwear

Ribs

The raised continuous or semicontinuous rows of rubber that run around the circumference of the tire tread

Grooves

The deep channels or spaces, either running around or across the tire that separate tread ribs and blocks

Track width

Measured from the center of the tread of a tire to the center of the tread of the opposite tire. This is different between front and rear tires

Wheelbase

The distance between the center of the front wheel and the center of the rear wheel

Turning diameter

Turning diameter of the smallest circle that can be driven by a vehicle (minimal space required for a car to make a 360)

Electrostatic dusting and gel lifting

What are the methods of collecting latent impressions?

Electrostatic dusting

Use of static electricity to trap dust on shoe impressions on lifting film that can be viewed with a special light source

Gel lifting

Used with a layer of gel sandwiched between paper backing and a plastic cover sheet; the print is first dusted with powder and the gel side of the collection sheet is pressed firmly on the print

Casting

What are the method(s) of collecting plastic impressions?

Plaster of Paris impression

What type of casting impression would be made if the impression is in sand or soil

Wax or dental stone

What type of casting impression would be made if the impression is in snow

What were the entrance and exit routes? How many people were at the crime scene? What is the estimated height and walking pattern of the individual?

What kind of information can shoe impressions tell you?

Why kind of car was being driven? What was the sequence of events? How fast was the car traveling?

What kind of information can tire impressions tell you?