Scientist from ChemImage and Oak Ridge National Laboratory discovered a field portable system that can detect, so far invisible, latent fingerprints on human skin. Whether to stop them from fleeing, immobilize them, or dispose of them, murderers often grab their victims, and so the crucial evidence linking the perpetrator to the victim is often right there, but until recently, attempts to retrieve those prints rarely met with success.
The skin posses a number of distinctive characteristics, that make lifting latent prints really hard. Skin tissue grows and constantly renews itself, shedding old cells that might contain the imprint of an assailant’s grip. As the skin regulates the body’s temperature and excretes waste matter through perspiration, latent prints can be washed away. In spite of the obvious difficulties, scientist have been looking for a reliable method throughout history (dating back in the 1970.) And all that research led to development of a workable method for developing identifiable latent prints on human skin.
Two methods that proved useful so far are: glue fuming device that spreads glue fumes over the skin and special brands of fingerprint powders. The new system though, takes advantage of surface-enhanced Raman spectroscopy (SERS)-based agents to visualize latent prints. A team led by Linda Lewis of ORNL’s Chemical Sciences Division is working with ChemImage to identify fingerprint components that are SERS active – those components that give a Raman emission when using a SERS reagent.
The ORNL team has identified a novel dielectric nanowire coated with silver as the SERS agent of choice.
All these methods for developing latent print on human skin work only if the body is examined soon enough, and give better results if the body was deceased when handled. Under ideal laboratory conditions prints could be obtained (one way or the other), but by inventing this method researchers wanted to make sure that practitioners in the field could obtain similar results. In real life though, victims are usually not found immediately, bodies are starting to decompose, various elements and harsh conditions influence the longevity of latent prints on skin. Even though, as we can see with all that’s been said, the chances might be small, it is highly recommended that if forensic scientists believe that perpetrator might have touched the victim, they should try to recover any possible latent prints on the victim’s skin.
-article by Ivan Ross Futrell updated from Science Daily, rewritten and adapted by administrator-