Technology inspired by a NASA space probe will soon be helping detectives solve gun crimes and murder cases far faster. A simple handheld device that instantly confirms whether a suspect has recently fired a gun means lab delays will not allow suspects time to get away.
The idea for the device was hatched under a new collaboration between NASA and the US National Institute of Justice. The plan is to adapt taxpayer-funded space research to fight terrestrial crime.
Jacob Trombka, a physicist at NASA鈥檚 Goddard Space Flight Center in Greenbelt, Maryland, set the ball rolling. He believes X-ray fluorescence (XRF) could be a key crime-fighting technology. It was used by NASA鈥檚 Near Earth Asteroid Rendezvous (NEAR) probe, which touched down on the asteroid Eros in February 2001.
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X-ray fluorescence spectrometry can identify the chemical elements in a substance by measuring the wavelengths it emits when exposed to X-rays. NEAR鈥檚 sensors simply recorded cosmic X-rays bouncing off the asteroid and beamed the details of the emissions back to Earth.
Trombka believes a handheld forensic tool could work along similar lines, taking X-ray fluorescence readings at the scene of a crime and beaming them to a computer for instant analysis. This way, forensics experts could quickly detect traces of blood, semen or gunshot primer on suspects鈥� hands. Gunshot primer is a chemical that converts kinetic energy from the gun鈥檚 hammer into heat to ignite the gunpowder.
Non-destructive
One benefit of this approach is that measuring X-ray emissions would not destroy the physical evidence, as analysing a swab can often do.
鈥淩ight now we have no method of doing this,鈥� says Carl Selavka, from Massachusetts State Police Crime Laboratory, who has been working with Trombka on this research. 鈥淚t could also be quite helpful in investigating suicides,鈥� he says, because roughly half of all murder investigations turn out to have been suicides. If there is gun residue on the victim鈥檚 hand, it鈥檚 likely they fired the fatal shot.
Unlike NEAR鈥檚 XRF system, the portable unit has to have its own diminutive X-ray source.
The device will compare its spectral readings with an onboard database, or failing that beam the information back to a forensics computer for more detailed analysis. Either way it should only take a few minutes and give crime teams reliable enough feedback to arrest a suspect 鈥� or not.
Gunshot primer or solder?
Trombka found XRF particularly useful for identifying residue from gunshot primer, which can be difficult to detect, even in the lab. Traces of antimony and barium can come from gunshot primer, but may also be found on the hands of people working in jobs where they come into contact with brake fluid or solder.
However, Trombka found that these elements bind together with the rapid temperature changes they undergo when a gun is fired. So he can identify the residues as gunshot primer by checking if the barium and antimony are bound together. 鈥淚t鈥檚 a fingerprint of the high-temperature process,鈥� he says.
But the real triumph could be XRF鈥檚 ability to detect substances without destroying the samples. It might even spot blood or semen on walls that have since been painted over. However, the device still needs to be made smaller, he says. 鈥淏ut by 2003 we should be testing it in real situations.鈥�