Forensic disciplines combine to develop new fingerprinting technique that could help spot document fraud
As one of the foremost innovators within the fields of fingerprint evidence and forensic document examination, researchers at foster+freeman have plenty of combined experience when it comes to developing new technologies for the investigation of crime.
However, while it is not un-common for existing methods and techniques to be re-purposed or enhanced to improve results, it is rare that two independent forensic disciplines combine so well as is the case with the company’s latest invention – a unique gelatin fuming technique for examining fingerprints on documents.
Combining a common fingerprinting practice (known as gelatin (gel) lifting) with a novel fuming technique (previously used to reveal fingermarks on fired ammunition) the new technique can be utilised by investigators to determine the sequence in which print details and fingermarks were added to a document.
In a paper published by New Scientist, foster+freemans’ Dr Roberto King outlined how the new technique could be important in cases of fraud or in other situations where someone is suspected of tampering with a will or contract by printing on top of it.
To use the technique, a technician places the gelatin over a fingerprint that overlaps with some printed text. They then peel off the gelatin and place it inside a vacuum-sealed glass box filled with a vapour of a chemical called disulphur dinitride. This vapour binds to the microscopic fingerprint ridges imprinted on the gelatin’s surface so that after a few minutes a blue-coloured fingerprint is revealed.
The team tested this process for a fingerprint that had text printed over it and another that was made on top of printed text. In the former case, the gelatin touches the text instead of the fingerprint first so the pattern developed at the end of processing was noticeably different – the team could tell which came first, the fingerprint or the text.
Importantly, the technique relies on pre-existing and widely available technology and would not require extensive further training. In addition to this, the new technique can be combined in sequence with other forensic techniques such as gelatin lifting and does not destroy the fingerprint.
King, R.S.P., McMurchie, B., Wilson, R. et al.
Published: 21 July 2022
LATENT FINGERPRINT TECHNOLOGY
RECOVER LFT is a cutting-edge chemical vapor fuming process to develop fingerprints on a range of difficult surfaces including those that have been exposed to extreme heat (discharged bullet casings, for example) and items that have been washed ‘clean’ in an attempt to prevent identification.
“This discovery gives us the ability to recover fingerprints from items that would have been previously difficult or impossible. It has shown particularly good results when used on fired ammunition cases, knives and contaminated metallic items”Steve Bleay, MoD Defence Science and Technology Laboratory