Canadian Researchers Use Slime to Pull Better Forensic Fingerprints

Slime is poised to become the next big thing in fingerprint forensics. At least, that’s the case being made in a new study that is set to appear in the June 2020 issue of the forensic journal Identification Canada. The independent study is based on techniques that were initially developed by forensic investigator Caleb Foster, and was written by University of Toronto Mississauga forensic science graduate Leanne Byrne in collaboration with U of T forensic identification instructor Wade Knapp and lab technician Agata Gapinksa-Serwin.

The paper itself explains how forensic investigators would be able to use slime to obtain better fingerprint samples from various surfaces. The slime in question would be made with recipes comparable to the ones that are currently popular with children, and would include a chemical reagent to create a stain that makes a fingerprint easier to see.

At the moment, forensic investigators typically use liquid sprays to achieve that effect, but the process is messy and wasteful since the solution doesn’t always land on the print. The slime, on the other hand, is more precise and can be reapplied almost immediately if necessary.

“Reagent agents in the slime reacts with the fingerprint, producing a stain that enhances the detail so we can photograph it,” explained Byrne. “My method proposes an inexpensive technique that uses borax mixed with glue as the baseline compound. With this method, investigators can press the slime on the fingerprint, wait a couple of seconds and lift it up.”

The study specifically looked at two common reagent chemicals (crystal violet and amido black), which were tested on bloody and non-bloody prints on different kinds of tape and on painted wood tiles. The results were better on some surfaces than they were on others, prompting Byrne to call for additional testing with other surfaces and reagents. She also noted that they would need to be able to account for factors like age and humidity before deploying slime in the field.

The new research arrives after a 2019 study from researchers at the University of Nottingham and the University of Derby detailed how Time-of-Flight Secondary Ion Mass Spectroscopy could be used to read fingerprints on metal surfaces. Fingerprint forensics also recently helped lead to an arrest in a murder investigation that had been unsolved since 1975.

Source: University of Toronto

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June 22, 2020 – by Eric Weiss