Footwear and Tiretrack Impressions

Question 1

In what ways can shoe prints aid an investigation?

6

Answer 1

• Type of shoe
• Pattern design
• Minimum number of suspects
• Connections to other crime scenes
• Sequence of events - directionality
• Corroborate versions of events

Question 2

What is the purpose of the Scientific Working Group on Shoe and Tire Tread Evidence?

Answer 2

Provide a professional forum where forensic shoeprint and tire tread examiners can share knowledge, evaluate practices, develop standards, identify research needs and disseminate information.

Question 3

Define a 2D impression

Answer 3

An impression, which for all practical purposes, has the dimensions of length and width but not a significant depth.

Question 4

What are the two types of 2D footwear impressions classified based on substrate?

Answer 4

Transfer/positive
Take-away/negative

Question 5

What are transfer/positive impressions?

Answer 5

Transfer of material onto a surface.

Question 6

What is a take-away/negative impression?

Answer 6

Shoe removes material from the substrate.

Question 7

What are the two types of 2D footwear impressions classified based on origin?

Answer 7

Wet-origin
Dry-origin

Question 8

What is a wet-origin impression?

Answer 8

Wet/dry matrix transferred onto wet/dry substrate.

Question 9

What is a dry-origin impression?

Answer 9

Dry matrix transferred to dry substrate or dry matrix taken away.

Question 10

When in doubt about whether a print is of wet or dry origin, what is best practice?

Answer 10

Assume impression is of dry origin because any enhancement may destroy the impression.

Question 11

What is a 3D impression?

Answer 11

An impression with the dimensions of length, width and depth.

Question 12

What is a general/class characteristic?

Answer 12

An intentional or unavoidable characteristics that repeats during the manufacturing process and is shared by one or more other shoes or tires.

Question 13

For what purposes can general/class characteristics be used?

Answer 13

Elimination purposes.

Question 14

Give examples of class characteristics.

5

Answer 14

• Tread pattern
• Type of footwear
• Size
• Wear pattern
• Defects indicative of the manufacturing process

Question 15

What determines if a manufacturing defect is a class/general characteristics or RAC?

Answer 15

How many shoes are made with that defect

Question 16

Why is wear pattern considered a class/general characteristic and not a RAC?

Answer 16

They are not random and are expected to happen.

Question 17

What are randomly acquired characteristics?

Answer 17

Result when something is randomly taken from or added to the original structure of the shoe or tire that either causes or contributes to making that shoe or tire unique.

Question 18

For what purposes can RACs be used?

Answer 18

Identification purposes.

Question 19

Give examples of RACs.

4

Answer 19

• Cuts
• Chips
• Tears
• Foreign materials or objects

Question 20

What assists RACs in identification?

2

Answer 20

Physical shapes
Spatial relations

Question 21

What are the three possible conclusions of fingerprint analysis?

Answer 21

Identification
Exclusion
Insufficient detail

Question 22

Why are fingerprint conclusions more definitive than shoeprint conclusions?

Answer 22

Footwear has many more variables

Question 23

List the variables in shoeprints that make analysis less definitive.

9

Answer 23

• Is the shoe still in production?
• Years it was produced
• How long since production ended
• How many were made
• Were the outsoles used for one shoe style or more
• Were the outsoles used by one company or more
• Was the mold sold to another company after production ended?
• Where is the shoe available?
• Footwear is always changing.

Question 24

How is footwear detected?

Answer 24

Light

Question 25

White type of light can be used to detect footwear? | 5

Answer 25

Ambient White Oblique ALS Laser

Question 26

What is grazed lighting?

Answer 26

Lighting held parallel to a surface.

Question 27

What is oblique lighting?

Answer 27

Light held at an angle to the surface (but not 90 deg)

Question 28

What are some requirements for photographing footwear impressions? | 4

Answer 28

* Scale must be at same plane as impression * Photograph at 90 deg angle * Tripod must be used * Fill the frame

Question 29

What is a good technique for obtaining the best photograph of a footwear impression?

Answer 29

Take multiple photographs with different angles of off-camera flash

Question 30

True or false: Only photograph footwear impressions with scale

Answer 30

False Take photographs both with and without scale

Question 31

What should be done if an impression to be photographed is vertical?

Answer 31

Make the camera vertical

Question 32

Why is it important that footwear impression be depicted with a sharp and detailed image?

Answer 32

Analysis will be performed

Question 33

What is depth of field?

Answer 33

The acceptable sharpness of an image

Question 34

How is depth of field controlled?

Answer 34

Aperture

Question 35

What is the appropriate depth of field for footwear analysis photography?

Answer 35

F16+

Question 36

What are the two main methods for enhancing foot wear impressions? Are these methods destructive or non-destructive?

Answer 36

1. Fingerprint powder 2. Chemistry Both are destructive

Question 37

Give examples of chemical footwear enhancement techniques. | 4

Answer 37

* Blood reagents * Bromophenol blue * Potassium thiocyanate * Iodine fuming

Question 38

What should be considered when deciding what enhancement method should be used for footwear?

Answer 38

If the print is of wet- or dry-origin Substrate

Question 39

True or false: Always develop an impression as much as possible.

Answer 39

False, always underdevelop an impression

Question 40

What type of situations are good for enhancing an footwear impression with powder?

Answer 40

Wet-origin impressions on hard surfaces, make sure to dry before developing

Question 41

What type of footwear impressions are suitable for development with magnetic powder?

Answer 41

Wet-origin impressions on paper

Question 42

What should be considered when selecting the appropriate powder for footwear impression enhancement?

Answer 42

Contrast with background

Question 43

What materials can be used to enhance footwear impressions made in snow? | 2

Answer 43

Black powder Paint

Question 44

What is the best practice for collecting 2D footwear impressions?

Answer 44

Physically remove the substrate with the impression and preserve it

Question 45

What methods can be used for lifting 2D footwear impressions? | 4

Answer 45

* 4'' fingerprint tape on acetate or backing card * Electrostatic dustlifter * Gel lifter * Dental Stone (Knaap process)

Question 46

Outline the process of lifting a footwear impression with ESDL. | 3

Answer 46

1. Place sheet of lifting film over footwear impression 2. Add charge to lifting film 3. Dust particles attracted to film

Question 47

For what type of impressions is ESDL lifting useful?

Answer 47

Dry-origin impressions on non-metal substrates

Question 48

What is important to remember regarding the lifts resulting from ESDL?

Answer 48

The lifts are horizontally flipped.

Question 49

Outline the Knaap process.

Answer 49

A typical dental stone mixture is poured over the powdered impression Once cured, the stone retains the impression.

Question 50

For what types of surfaces is the Knaap Process useful?

Answer 50

Dimpled surfaces

Question 51

What is the quality of impressions left in snow influenced by? | 5

Answer 51

1. Temperature 2. Type of snow 3. Exposure to direct sunlight or shaded 4. Quality of the footwear 5. Wind

Question 52

Why is dental stone not used to lift impressions left in snow?

Answer 52

Undergoes an exothermic reaction that would melt the snow.

Question 53

Describe the similarities between casting with sulphur and dental stone. | 2

Answer 53

Both make successful casts in snow and both have the ability to record a high level of detail.

Question 54

How do sulphur and dental stone differ in size and/or number of casts?

Answer 54

Dental stone can be mixed in large quantities while sulfur is best used with one or two casts at a time

Question 56

How do sulfur and dental stone differ in their hardening times?

Answer 56

Sulfur takes longer to prepare, but completely hardened and ready to be picked up much faster.

Question 57

What other factors might be considered when choosing between sulfur and dental stone? | 5

Answer 57

* Hazards/toxicity * Travel requirements * Training * Experience * Materials

Question 58

What is SICAR and what does it stand for?

Answer 58

SICAR = Shoeprint Image Capture And Retrieval An automated shoe print identification system

Question 59

How does SICAR work?

Answer 59

Incorporates multiple databases to search known and unknown footwear files for comparison against footwear specimens.

Question 60

What databases are used in SICAR? | 2

Answer 60

Sole Mate and Tread Mate

Question 61

Do tire track impression have development techniques similar to those of footwear?

Answer 61

Yes

Question 62

What is the pretense of using fingerprint powder to develop tire track impressions?

Answer 62

Fingerprint powder will have an affinity to moisture deposits in the impression

Question 63

Give examples of moisture deposits in tire impressions. | 4

Answer 63

Water Grease Oil Tire rubber reside

Question 64

What agnecy has the largest tire track database in the world?

Answer 64

RCMP

Question 65

How are 3D tire tracks collected?

Answer 65

With dental stone

Question 66

What things should be considered when regarding tire track impressions? | 6

Answer 66

* Tire track width * Wheelbase dimensions * Turning diameter * Relative position of turning tracks * Make and model tire frequencies on vehicles * Effects of deflation