Significance of Class Significance of Class Association of Shoe PrintsAssociation of Shoe Prints

Sandy ParentSandy Parent

Texas Department of Public SafetyTexas Department of Public Safety

What is the likelihood that What is the likelihood that two people would have a two people would have a

shoe similar in tread shoe similar in tread pattern, size and wear and pattern, size and wear and wear the shoe to the same wear the shoe to the same

place on the same day?place on the same day?

Random Population Random Population

Various ages Various ages Males and Females Males and Females Various professions Various professions Various income levelsVarious income levels Various originsVarious origins

= Many different types of footwear = Many different types of footwear

Texas Department of Public Texas Department of Public Safety Driver’s License Safety Driver’s License

BuildingBuilding Study 1: Study 1: July 2004 (3 July 2004 (3 days)days)

AustinAustin

Study 2:Study 2: March 2005 (2 days)March 2005 (2 days) AustinAustin GarlandGarland HoustonHouston LubbockLubbock McAllenMcAllen

Austin▲ Houston

▲ Garland

▲ Lubbock

▲

McAllen

Austin

Collection Collection Individuals were asked to participate in Individuals were asked to participate in

studystudy Right shoe sole Right shoe sole Documented information: Documented information:

ManufacturerManufacturer Style (Dress, Casual, Athletic, Sandal, Style (Dress, Casual, Athletic, Sandal,

Boot)Boot) SizeSize Male / FemaleMale / Female

““Invisible Ink” Method – Armor HoldingsInvisible Ink” Method – Armor Holdings

Invisible Ink MethodInvisible Ink Methodby Armor Holdingsby Armor Holdings

1607 Shoe Prints1607 Shoe Prints Study 1 – Study 1 –

July 2004 – 3 days July 2004 – 3 days

Austin, TXAustin, TX

555 Shoe Prints555 Shoe Prints

Study 2 – Study 2 –

March 2005 – 2 DaysMarch 2005 – 2 Days

236 Shoe Prints / Austin236 Shoe Prints / Austin

205 Shoe Prints / Garland205 Shoe Prints / Garland

236 Shoe Prints / Houston236 Shoe Prints / Houston

181 Shoe Prints / Lubbock181 Shoe Prints / Lubbock

194 Shoe Prints / McAllen194 Shoe Prints / McAllen

Total – Total – 1052 Shoe Prints1052 Shoe Prints

Study 1 – 555 Shoe PrintsStudy 1 – 555 Shoe Prints

Athletic Shoes – Athletic Shoes – 207207

Sandal – 204Sandal – 204 Casual – 84Casual – 84 Boot – 32Boot – 32 Dress – 27Dress – 27 Unknown – 1Unknown – 1

0%5%

10%15%20%25%30%35%40%

Study 2 – 1052 Shoe PrintsStudy 2 – 1052 Shoe Prints

Athletic – 430Athletic – 430 Sandal – 129Sandal – 129 Casual – 261Casual – 261 Boot – 133Boot – 133 Dress – 99Dress – 99

0%5%10%15%20%25%30%35%40%45%

Study ComparisonStudy Comparison

0%

5%10%

15%

20%25%

30%

35%40%

0%5%10%15%20%25%30%35%40%45%

Study 2

Study 1

OVERALL – 1607 Shoe PrintsOVERALL – 1607 Shoe Prints

Athletic – 637Athletic – 637 Sandal – 333Sandal – 333 Casual – 345Casual – 345 Boot – 165Boot – 165 Dress – 126Dress – 126 Unknown - 1Unknown - 1

0%5%10%

15%20%25%

30%35%

40%

Market AnalysisMarket Analysis

Athletic Athletic Nike 157Nike 157 New New

Balance Balance 6565

Reebok 60Reebok 60 Adidas 41Adidas 41 K Swiss 26K Swiss 26 Skechers Skechers

3232

CasualCasual Skechers Skechers

1818 Polo 16Polo 16 Rockport 15Rockport 15

SandalsSandals Reef 21Reef 21 Old Navy Old Navy

1818

Male Shoe SizesMale Shoe Sizes

Size 7 – 18Size 7 – 18

Size 7.5 – 23Size 7.5 – 23

Size 8 – 43Size 8 – 43

Size 8.5 – 59Size 8.5 – 59

Size 9 – 102Size 9 – 102

Size 9.5 – 80Size 9.5 – 80

Size 10 - 105Size 10 - 105

Size 10.5 – 95Size 10.5 – 95

Size 11 – 91Size 11 – 91

Size 11.5 – 32Size 11.5 – 32

Size 12 – 86Size 12 – 86

Size 12.5 – 3Size 12.5 – 3

Size 13 – 51Size 13 – 51

Size 14 - 13Size 14 - 13

* Based on information provided by participant

Female Shoe Sizes Female Shoe Sizes

Size 5 – 19Size 5 – 19

Size 5.5 - 22Size 5.5 - 22

Size 6 – 46Size 6 – 46

Size 6.5 – 44Size 6.5 – 44

Size 7.0 - 114Size 7.0 - 114

Size 7.5 – 77Size 7.5 – 77

Size 8 – 107Size 8 – 107

Size 8.5 – 73 Size 8.5 – 73

Size 9 – 81Size 9 – 81

Size 9.5 – 29Size 9.5 – 29

Size 10 - 39 Size 10 - 39

Size 10.5 – 3Size 10.5 – 3

Size 11 – 13Size 11 – 13

* Based on information provided by participant

““Class CharacteristicClass Characteristic – An – An intentional or unavoidable intentional or unavoidable

characteristic that repeats during characteristic that repeats during the manufacturing process and is the manufacturing process and is

shared by one or more shoes”shared by one or more shoes”

- Bodziak, William - Bodziak, William Footwear Impression Evidence Detection, Recovery, and Footwear Impression Evidence Detection, Recovery, and

ExaminationExamination

Tread Pattern, Size and Wear Tread Pattern, Size and Wear

Tread PatternTread Pattern Gross DesignGross Design

Variation in the Manufacturing Variation in the Manufacturing ProcessProcess Mold vs. CutMold vs. Cut

TextureTexture StipplingStippling Chemical Acid EtchingChemical Acid Etching

Limitations Limitations Featureless solesFeatureless soles Large amount of wearLarge amount of wear Partial imprintsPartial imprints

Elimination – Tread PatternElimination – Tread Pattern

Elimination – Tread PatternElimination – Tread Pattern

Elimination – Tread PatternElimination – Tread Pattern

Elimination – Tread PatternElimination – Tread Pattern

Elimination - Tread PatternElimination - Tread Pattern

Elimination – Tread PatternElimination – Tread Pattern

Elimination – Heel TreadElimination – Heel Tread

Elimination - Tread PatternElimination - Tread Pattern

Size / DimensionsSize / Dimensions

Physical Dimensions of the imprintPhysical Dimensions of the imprint Not related to the manufacturer sizeNot related to the manufacturer size Superimpose imprints (Overlay Superimpose imprints (Overlay

Method)Method) Limitations –Limitations –

Partial imprintsPartial imprints Heavily saturated imprintsHeavily saturated imprints

Elimination – Size Elimination – Size

ReebokSize 8

M

ReebokSize 2.5

M (Youth)

WearWear The effect of frictional or abrasive The effect of frictional or abrasive

forces on the shoe soleforces on the shoe sole The removal of portions of the design The removal of portions of the design Noticeable differences in the worn Noticeable differences in the worn

versus unworn areas of the shoesversus unworn areas of the shoes Position and degree of wearPosition and degree of wear Schallamach PatternSchallamach Pattern Limitations:Limitations:

Undefined or minimum amount of wearUndefined or minimum amount of wear Heavily saturated imprintHeavily saturated imprint

Schallamach PatternSchallamach Pattern

Elimination by WearElimination by Wear

Elimination - WearElimination - Wear

Elimination – Overall SizeElimination – Overall Size

Old Navy – Flip FlopsOld Navy – Flip Flops

13 Shoes / 78 Possible Pairs

Indistinguishable Pairs: Tread - 4 Size / Dimensions - 2 Wear - 0

Reebok8 shoes

Reebok3 shoes

Manufacturer: SkecherNumber Collected: 10Possible Pairs: 45

Indistinguishable Pairs:

Tread Pattern – 45 pairsSize – 1 pairWear - 0

Manufacturer: New BalanceNumber Collected: 8 Possible Pairs: 28

Indistinguishable Pairs:

Tread Pattern – 28 pairsSize - 0Wear – Not Applicable

Manufacturer: New BalanceNumber Collected: 7Possible Pairs: 21

Indistinguishable Pairs:

Tread Pattern – 6 Size - 0Wear – Not Applicable

Tread Pattern - EliminationTread Pattern - Elimination

ComparisonComparison Local PopulationsLocal Populations Total PopulationTotal Population

Assess the Significance based on:Assess the Significance based on: Toe AreaToe Area

Tread design Tread design Size/Dimensions Size/Dimensions Wear Wear Toe + Heel Toe + Heel AreaArea

Tread design Tread design Size/Dimensions Size/Dimensions Wear Wear

Study 1 - 2004555 Shoe Prints

153735 Possible Matches

Toe Toe + Heel

Tread Pattern -122 (81)

Size / Dimensions -

91 (81)

Tread Pattern -35 (0)

Size / Dimensions -

0 (0)

Wear -16 (15)

Wear -Not Applicable

*( ) = Featureless soles

Indistinguishable PairsIndistinguishable Pairs

04 0.02%

N/A2 0.01%

05 0.02%

06 0.03%

 N/A 90.03%

WearWear

20.01%

350.19%

0180.11%

1 0.0%

25 0.09%

3 0.01%

180.08%

 020 0.07%

Size Size

16 0.09%

430.23%

11 0.07%

290.18%

24 0.09%

440.16%

240.11%

360.17%

70.03% 

300.11%

TreadPattern

TreadPattern

194 / 18721

181 / 16290

236 / 27730

205 / 20910

236 / 27730

McAllen

Lubbock

Houston

Garland

Austin

# prints /possiblepairs

Toe and HeelToe

*( ) = Featureless soles

1607 Shoe Prints1290421 Possible Pairs

Toe Toe + Heel

Tread Pattern -1521 (961)

Size / Dimensions -1079 (961)

Tread Pattern -536 (29)

Size / Dimensions -

38 (10)

Wear -252 (232)

Wear -0

Indistinguishable PairsIndistinguishable PairsToe Toe and Heel

# ofimprints

/Possiblepairs

TreadPattern Size Wear

TreadPattern Size Wear

Study 1555 /153735

1220.08%

910.06%

16 0.01%

35 0.02% 0 N/A

Study 21052 /552826

873 0.16%

621 0.11%

155 0.03%

312 0.06%

25 0.005% 0

Overall1607 /1290421

1521 0.12%

1079 0.08%

252 0.02%

536 0.04%

38 0.003% 0

What is the likelihood that What is the likelihood that two people would have a two people would have a

shoe similar in tread shoe similar in tread pattern, size and wear and pattern, size and wear and wear the shoe to the same wear the shoe to the same

place on the same day?place on the same day?

State of Alaska Crime LabState of Alaska Crime Lab-Lesley Hammer & Janeice -Lesley Hammer & Janeice

AmickAmick Collected right shoe imprint from 353 Collected right shoe imprint from 353

individuals at the local DMV in 2006 individuals at the local DMV in 2006 Majority appeared to be athletic footwearMajority appeared to be athletic footwear Unable to infer age of person from shoe Unable to infer age of person from shoe

imprints imprints Similar design worn by 15 year old & 45 year oldSimilar design worn by 15 year old & 45 year old Similar design and size worn by 44 yo & 77 yoSimilar design and size worn by 44 yo & 77 yo

Results – 1 pair was determined to be Results – 1 pair was determined to be indistinguishable based on design and sizeindistinguishable based on design and size Adidas – size 7.5 – 16 year oldsAdidas – size 7.5 – 16 year olds Appeared to have same stippling in a small area Appeared to have same stippling in a small area

Special Thanks To:Special Thanks To:

Allen Miller – Armor ForensicsAllen Miller – Armor Forensics Christi Wells & Greg JellikChristi Wells & Greg Jellik Micheal Villarreal, Jose Zuniga, Devin Micheal Villarreal, Jose Zuniga, Devin

Crago and Lan Bundy Crago and Lan Bundy TX DPS ManagementTX DPS Management William Bodziak William Bodziak

Contact InformationContact Information

Sandy ParentSandy Parent

P.O. Box 4143 MSC 0460P.O. Box 4143 MSC 0460

Austin, TX 78765-4143Austin, TX 78765-4143

(512) 424-2105 (512) 424-2105

Sandy.Parent@txdps.state.tx.usSandy.Parent@txdps.state.tx.us