Forensic Footwear Evidence Ch 18 Pgs 361-375. Terminology Two-dimensional Impressions – Print that has length and width but no significant depth Footwear.

Forensic Footwear Evidence

Ch 18 Pgs 361-375

Terminology Two-dimensional Impressions – Print that

has length and width but no significant depth Footwear databases – Computerized

compilation of shoe sole designs for the purpose of associating a crime scene impression with a manufacturer or to link it to another crime scene

Electrostatic Lifting – Using a high voltage device to electrostatically transfer a dry-origin dust or residue impressions to a black film

Dry-Origin Impression – Impression that contains no significant moisture from itself or its substrate when made.

Wet Origin - Impression containing significant moisture from the shoe sole or its substrate when made.

Dental Stone – gypsum product, similar to plaster of Paris. (Hard and durable)

Test Impressions – Impression made by using a known shoe or tire as a standard; used in the examination of shoe and tire impressions

I. Introduction1. As persons walk about, their shoes track over hard

surfaces acquiring : Dust, dirt, residue, grease, blood, oils, paint, or

moisture Shoes then re-deposit these material back onto other

surface as they track over it

2. Two types of prints can be left: Patent (visible) Latent (invisible)

3. Regardless of the type of surface, there is a transfer of both class and individual characteristics

These will help Forensic Scientist determine if a suspect’s footwear made the impression to a scene, or if it can be eliminated

4. The process includes: The detection and

recovery of the footwear evidence from the scene of the crime

Enhancing that evidence if appropriate

Producing known impressions of the shoes being examined

Comparing the crime scene impressions with the footwear

5. Footwear impressions are routinely used to prove a suspect was present at the crime scene.

Most frequently used in crimes were proof of the suspects presence is incriminating……homicides, burglaries, assaults, robberies, rapes,….

II. Forms of Footwear Impressions1. There are two forms of Footwear

impressions;1. Three-Dimensional Impressions2. Two-Dimensional Impressions

2. Three-Dimensional Impressions are those that remain after a shoe has permanently deformed a surface

Predominantly found on exterior surfaces such as sand, soil, or snow

Can be shallow or very deep

3. The resulting quality and impressions detail of a 3-D print depends on: composition of the

substrate in which the print was left

the amount of moisture

presence of contaminants..sticks, stones, debris

Two-Dimensional Prints 4. Two-dimensional

impressions are those made on non-giving surfaces, such as tile, linoleum, or wood flooring, includes those made on paper,

plastics, doors, carpet, clothing, broken glass, countertops,

a large number of both porous and non-porous surfaces can be stepped on or kicked by an item of footwear

5. 2-D impressions can be varied because the shoe may contain combinations of dust, dirt, soil, residues, grime, oils, or blood Makes the methods of

recovering harder

6. Some prints can be highly visible, others can be latent

7. Regardless of the type of print, the examination results depend on the detail retained in the impression

III. Information from Footwear Impressions

The following information may be obtained from footwear impressions:

#1 Identification of Footwear Prove suspect was at the crime scene

#2 Elimination of Footwear Based on differences in class characteristics

#3 Participation in the Crime Can prove suspects

presence at a crime scene

#4 Location of Impressions Can show point of entry/exit

and insight to locations of other evidence

#5 Rebuttal or Confirmation of Suspects Alibis Prove suspects is lying or

telling the truth

#6 Determination of Shoe Brand Brand and description can be determined through

a footwear database http://www.fosterfreeman.com/products/shoeprints/ShoeTyreEvidenceUK.pdf

#7 Linking Scenes of Crime Useful in investigations of repetitive crimes

#8 Determination of Shoe Size If manufacture is known an accurate

determination of size can be made

#9 Number of Perpetrators The number of prints recovered can indicated whether

a group of criminals or an individual committed the crime

#10 Association with Other Evidence Backtracking can help locate other evidence

#11 Gait Characteristics Gait analysis us primarily use for persons with a

walking problem The measurement of a persons stride, step, and length

can change Not a reliable means of identification http://images.google.com/imgres?imgurl=http://www.forensicgait.com/sub/images/sub_menu_pic.gif&imgrefurl=http://www.forensicgait.com/

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#12 Tracking Tracking involves following the path of an

individual by observing evidence that the person has created as he/she passes over various surfaces Includes shoeprints, footprints, crushed debris,

displaced rocks, sticks or leaves that may have been stepped on

Most commonly used for tacking illegal aliens and missing children

Trackers are usually trained at the US border patrol

IV. Location and Recovery of Footwear Impressions

1. It is critical that proper techniques be used to locate, document and recover footwear evidence Otherwise its evidentiary value is lost

2. Success in locating the shoeprint and recovering maximum detail from each impression has a direct impact of the usefulness of the evidence.

3. Impressions may be full or partial. Partial prints may only be a small percentage It may contain enough detail to be identified or

eliminated

4. An impressions value will not be known until it is fully recovered, enhanced, examined, and compared with shoes.

5. Most impressions are found on floor surfaces Critical that the scene is secured

6. Some impressions are obvious (bloody prints next to a victim), others will require a more deliberate effort to locate.

a. Locating impressions7. Methods of locating an impression:

i. slow visual search, followed by darkening the room and using a high-intensity oblique lighting source

ii. Application of an electrostatic lifting device

iii. Closely examine any items that may have been stepped on

Paper items usually contain high amounts of latent dust, broken glass usually contain high amounts of detail, but needs a special lighting source

iv. Exterior surfaces, especially near logical entry/exit points

8. Crime scene notes should provide the location, direction, and description of prints.

9. Notes should coincide with photographs to help reconstruct the sequence of events.

10. Any impression at a crime scene that can be safely recovered should be taken to the lab. Examination photographs are

used for prints that cannot be recovered

b. Lifting 2-D footwear prints1. Once an impression has been photographed it

can be lifted. Lifting improves the visibility and detail Enables the removal of the impression to the lab

2. Electrostatic Lifting By passing a current of 10,000- 15,000 volts across

footwear evidence, you cause the particles that make up the evidence to transfer to lifting film

3. Fingerprint powder in combination with mikrosil may be used on impressions where electrostatic lifting does not work

c. Lifting 3-D footwear prints1. Dental stone is primary

means of casting footwear impressions On wet surfaces, a spray

wax may have to be used first to seal impression

Mix dental stone with water in a ziplock bag for 3 minutes

Stone hardens in 20 minutes

In 24-48 hours it will have fully hardened

V. Enhancement Methods1. Poor impressions may have to be enhanced by

one of the following means: Forensic Photography – oblique, ultraviolet,

infrared or other special methods Physical Methods – latent powder, lifting

impressions, or impressions on paper Chemical Methods – reagents such as leuco

crystal violet, amido 10 black, luminol or fuschin acid may be used to enhance bloody prints

Digital Methods – Software such as Adobe Photoshop can be used to enhance impressions

(LCV) leuco crystal violet

diaminobenzidine

VI. Known Shoes and Preparation of Exemplars1. Footwear from Suspected Persons:

All footwear a suspect owns should be seized for comparison Shoes are needed to make test impressions

2. Elimination Footwear Footwear worn by police officers, medical personnel should be

accounted for when considering impressions left at scene

3. Known Test Impressions of Footwear Examiner will make impressions of known footwear and

compare them with suspected footwear impression to insure matching samples are highly detailed, and have individual characteristics of shoes

VII. The Examination Process and Conclusions

1. Areas of footwear which are examined by analyst include: Design of shoe Physical Size and Shape Wear marks Individual Identifying

Characteristics- cuts tar, gum etc