Impact of Snow on Latent Fingerprint Quality
A recent study has shown that snow can quickly damage latent fingerprints, making them difficult or even impossible to use for identification. Fingerprints rely on small details called minutiae, but these are easily affected by moisture, melting snow, and friction.
What the Study Looked At
Researchers wanted to understand how snow affects fingerprint quality. They collected 265 groomed latent fingerprints from a single donor to keep the residue consistent. These prints were then exposed to two winter conditions:
- Natural Snowfall: Fingerprints were left outside while snow fell naturally on them. This exposed them to cold temperatures, moisture, and melting snow.
- Snow Immersion: Fingerprints were placed directly into snow, similar to what happen if an object is dropped or handles in snowy areas.
After the exposure, the prints were developed using small particle reagent (SPR), a method that works well on wet surfaces.
Key Findings:
- 33% of fingerprints exposed to natural snowfall became non-usable
- 13% of fingerprints that were immersed in snow became non-usable
- Damage to ridge detail started after only 2 hours of exposure
Snow immersion was the most damaging condition because the meltwater quickly dissolved the fingerprint residue, while the ice crystals and friction physically disturbed the ridge patterns. In addition, repeated melting and refreezing cycles caused further distortion, leading to a rapid loss of usable minutiae.
Practical Recommendations
- Act fast: Collect fingerprints as soon as possible in snowy conditions.
- Prioritize sheltered areas: Look for prints under overhangs, inside vehicles, or on items that may have been partially protected.
- Use appropriate development methods: SPR is useful for wet surfaces, but it cannot recover severely damaged prints.
- Train for winter scenes: Teams should be prepared for faster fingerprint deterioration in snow.
This content is republished from Forensic Science Research (original article can be found here).
Note: Content has been adapted and edited for clarity.