An innovative recovery technique pioneered on ammunition rounds could transform fingerprint recovery during firearms investigations and provide investigators with a greater spectrum of evidence.
The groundbreaking process, which involves mixing a percentage of patination fluid with distilled water in a beaker before exposing the exhibit in the solution, has made significant advances in the recovery of fingerprints from ammunition where other techniques have failed.
Richard James, forensic practitioner in the Met’s Firearms Trace Evidence Recovery Unit, explained that previous chemical based techniques, including super glue fuming and a visual light box scan to identify areas of contamination, returned a dire recovery rate.
In 2013, out of 300 cases sent to the unit where ammunition was present, only one useable fingerprint was recovered.
However, Mr James’ collaborative project with Kings College London achieved an 83 per cent success rate of recovering marks of a sufficient quality to make a comparison with a suspect or use for a database search.
His research paves the way for the development of a simple, cheap and successful mark development technique which would prove vital in firearm investigations.
In an interview with Mr James said: “This process could save a large amount of time and money on wasteful processes that give nothing.
“It will add value to evidence and is a step forward for firearms investigations.
“It is so easy that once the chemical is made up anyone could do it. It could, if necessary, be done at a crime scene.
“Ammunition has been a problem in forensics as it is a very difficult surface to enhance fingerprints on. This is because it is a small surface area and exhibits get over handled and we do not get good results.
“If ever an area needed work this was it because we are not getting results back.”
Once the exhibit has been immersed in the three per cent chemical solution for a minute-and-a-half, Jade oil is then applied to halt the reaction and disperse moisture.
During the eight week project the solution was tested on 150 9mm rounds which were split into two groups. Once finger and thumb marks had been deposited on the ammunition, 75 were left for varying periods of time up to four weeks to try and replicate the conditions of a crime scene.
The remaining 75 rounds were fired from a pistol and the casings were recovered.
The most successful results were identified from the ammunition left over a period of time. However, the quality of the mark diminishes the longer it is left on a surface.
Of the 75 fired casings recovered, Mr James and his team were able to develop one useful finger mark. Despite the low result, this is still a significant improvement on previous techniques which had not been able to recover anything.
Mr James hopes that the process will go through a full validation before being used in live trials. He also hopes to pursue further work about the benefits the technique has on DNA sampling.
He added: “I did not think it would be as successful as it was. I assumed that we would get a recovery rate of around 20 per cent. I was amazed at how effective the method was.”