A comparison of three shoe sole impression lifting methods at high substrate temperatures

Area of Science:

• Forensic Science
• Trace Evidence Analysis

Background:

• Footwear impressions are crucial evidence in criminal investigations.
• Limited research exists on recovering impressions from hot surfaces (>30°C/86°F).
• Accurate recovery of class and randomly acquired characteristics (RACs) is vital for identification.

Purpose of the Study:

• To evaluate the effectiveness of common impression lifters on hot substrates.
• To compare gelatin, adhesive, and vinyl static cling film for recovering dust impressions.

Main Methods:

• Dust shoe sole impressions were made on ceramic tile, galvanized metal, and wood flooring.
• Substrates were heated in direct sunlight for five hours.
• Impression recovery was assessed by the proportion of visible class and randomly acquired characteristics (RACs).

Main Results:

• Vinyl static cling film performed poorly, especially on metal (23.8% marks recovered), showing shrinkage.
• Adhesive lifters achieved high success rates (~96% marks recovered across all substrates).
• Gelatin lifters also performed well (~85% marks recovered).

Conclusions:

• Adhesive lifters are recommended for consistent and accurate recovery of shoe sole impressions from hot substrates.
• This study provides essential data for improving evidence collection in warm climates.
• Findings enhance forensic capabilities in challenging environmental conditions.