5FO509 Object Marks: Shoe Marks Study Notes

Bodziak WJ. (2017). Forensic footwear evidence: detection, recovery and examination, 2nd Edition. Boca Raton: CRC Press.

Recognize shoe marks and their mode of deposition.
Understand optical, physical, or chemical techniques to detect and enhance shoe marks.
Know and recognize the different manufacturing and acquired characteristics of shoes, shoe marks, and prints.
Know the different exploitations of shoe marks.

Quote by Sir Arthur Conan Doyle (1887): “There is no branch of detective science that is so important and so much neglected as the art of tracing footsteps.” This highlights the historical significance of shoe marks in forensic investigation but notes their current neglect by crime scene investigators (CSIs) in the UK.
There exists a notable disparity in the effectiveness of police forces regarding shoe mark retrieval, with the highest performing police force achieving over ten times greater success than the lowest.
It was found that shoe marks taken from crime scenes were only routinely searched against other shoe mark records by a minority of CSIs, indicating a missed opportunity for generating intelligence and evidence.

Shoe marks rank among the top three types of physical evidence at crime scenes, alongside DNA and fingerprints.
Frequently encountered in various crimes such as burglaries, assaults, homicides, and outdoor crimes.
Shoe marks can manifest in three forms:
- Visible (patent): Clearly seen.
- Latent: Not visible without enhancement.
- Partially obscured: Covered by other debris or materials.

The documented use of shoe marks in forensic contexts dates back to the 17th century, as noted in Old Bailey transcripts.
Early forensic techniques involved directly comparing suspects' shoes at crime scenes, and prior to the advent of photography, tracings and sketches were relied upon to record impressions.
Modern forensic approaches have developed incorporating photography, casting, and expert analysis.

Historical court records detail a case in 1786 involving William Richardson, demonstrating early utilizations of shoe mark evidence in legal proceedings.

Definition: The principle of exchange asserts that the perpetrator of a crime will bring something into the crime scene and leave with something from it, and that both can be used as forensic evidence.
Key Notions:
- Intensity of traces produced by criminal activity.
- The notion of relevance in trace evidence; traces need to be located, recognized, and observed for them to be useful in forensic investigation.
- Criminals often inadvertently leave shoe marks as they are less likely to cover their footwear as opposed to actions such as wearing gloves or masks.

Footwear: Any item worn on the foot, including shoes, boots, sandals, slippers, and socks.
Shoe mark/Footwear mark/Footwear impression: The resultant mark from the outsole of footwear making contact with a surface, producing either a two-dimensional or three-dimensional impression.
- This can include:
- Deposition of contaminants from the footwear.
- Removal of material from the surface at points of contact.
- Compression of soft substrates during the contact.
Shoe print/Footwear print: The impression of the sole of a known shoe, typically collected by inking.
Footmark/Bare footmark: The impression left by the friction ridges of a human foot on a surface.

Two-dimensional shoe marks: consist of both positive (transfer impressions) and negative impressions due to material transfer or removal from the substrate.
Three-dimensional shoe marks: involve the permanent deformation of soft substrates such as soil, mud, sand, and snow.

Both two-dimensional and three-dimensional shoe marks necessitate enhancement treatments to improve visibility.
Marks can be photographed and lifted from scenes for further scrutiny.

A variety of light sources including infrared, ultraviolet, and laser can be employed.
Different illumination methods such as reflection and oblique lighting help enhance visibility by highlighting specific contrasts.
When examining dust particles, oblique lights create reflections by skimming the surface at low angles, allowing for better visibility of two-dimensional impressions.

Electrostatic Lifting (ESLA): This method attracts dust to the lifting surface to recover shoe marks without damaging the substrate. This technique is not suitable for wet marks.
Gelatin Lifts: Use sheets of gelatin on various backgrounds to facilitate recovery of shoe marks. The color chosen should depend on the desired contrast.
Casting: Commonly used for three-dimensional impressions, such as when dealing with soft materials like plaster of Paris or dental stone, which provide detail but are fragile and may require reinforcement.

Impressions can be enhanced chemically using various reagents to improve contrast against surfaces. Examples include:
- Leuco Crystal Violet (LCV): Enhances blood contaminants.
- 8-Hydroxyquinoline: Works with metal ions to form colored or luminescent complexes.

Understanding the construction and characteristics of shoe soles assists in identifying potential footwear sources. Key elements include:
- Size, shape, and general design features.
- Logos and inscriptions that denote brand or models.
- Mould characteristics and defects which can lead to unique identifiers in footwear.

Die Cutting: Involves cutting outsole material through a steel die.
Compression Moulding: An industry standard where rubber is pressed into moulds to create soles.
Injection Moulding: Most prevalent process where heated materials are injected into molds, allowing for greater design flexibility.

These arise from random and unplanned events during the use of footwear, such as:
- Wear due to walking: Results in specific abrasion patterns, including Schallamach abrasion.
- Embedded objects: Items such as stones or debris can become lodged in the outsole pattern.
Recognizing these characteristics is crucial for identification purposes in forensic analysis.

The study and recovery of shoe marks can have multiple applications in forensic investigations which can yield critical insights into criminal activities:
1. Establishing the type and profile of a suspect by interpreting shoe marks.
2. Reconstructing events based on collected shoe marks to understand the sequence of actions taken by suspects.
3. Linking multiple criminal cases through common shoe mark patterns, facilitating intelligence collection.
All findings are essential for warranting investigative leads and supporting courtroom testimony.