A remarkable new technique allows for detecting subtle clues on soft surfaces – something that has previously been hard to do.
The Scottish Police Services Authority are reportedly closer than ever to developing successful methods in recovering and identifying fingerprints from fabric. Teaming up with researchers from the University of Abertay Dundee, the ‘vacuum metal deposition’ technique uses gold and zinc to uncover fingerprint ridge detail and impressions – typically used on materials like glass and plastic.
Whilst only twenty-percent of fingerprints left are usable by investigators, the research has found that silk, nylon, polyester and high-thread-count fabrics are best for recovering prints.
Researcher Joanna Fraser explains the process;
The research uses fine layers of metals to display fingerprints people may have left on fabrics, something which is far harder to do with soft surfaces. The technique has been around since the 1970s and is used on many surface but was never widely used on fabrics.
We take these fabrics, place them in a vacuum chamber, then heat up gold to evaporate it and spread a fine film over the fabric. We then heat up zinc, which attaches to the gold where there are no fingerprint residues. This helps reveal the fingerprint – where contact has been made we see the original fabric, where there was no contact we’re left with the grey colour of the metal film.