The eerie blue glow of luminol on TV crime dramas could soon be replaced with a less dramatic, but far more revealing photograph.
Scientists from the University of South Carolina have created a new proof-of-concept camera that takes pictures of blood stains. If miniaturized and optimized, the new camera could be used by crime scene investigators to find the tiniest blood mists, and even detect whether a person handled drugs or explosives.
"It's called multimode imaging in the thermal infrared, and with it we have the capability to detect any kind of stain on any kind of surface," said Stephen Morgan, who, along with fellow professor Michael Myrick and several graduate students from University of South Carolina, developed the new blood revealing technology. Their research is detailed in the journal ACS Analytical Chemistry.
Finding a blood stain on surfaces is harder than it sounds. While TV cop shows like "CSI" and "Dexter" make prodigious use of luminol to make hidden traces of blood appear as if by magic, the reality is far more complicated, and not nearly as clear, said Morgan and David Foran, director of the Forensic Science Program at Michigan State University, who was not affiliated with the new study.
"It's not nearly as sensitive as it could be. You have to have the room completely dark to see the blood. It is short-lasting so you have to keep spraying the blood, which can then start to run," and it can react with things other than blood, such as rust, said Foran.
"If you had a system that didn't react and give false positive, that would certainly be an advantage," said Foran.
The new camera, which uses infrared light that is invisible to the human eye at a distance of three to six feet, is intended to avoid many of these complications and false positives.
By taking a photograph of the crime scene, and not spraying it down with a chemical that can cause blood stains to run, the scientists can preserve potentially valuable evidence and gain more information than was possible before.
The new camera can find blood stains on dark materials, like black cotton, where it might not be visible to the eye. It can also tell the difference between rust and blood, which would both cause luminol to glow blue, giving a false positive.
The new camera also finds smaller amounts of blood, such as very fine misting, which the human eye can't see, even with luminol. Depending on a criminal's level of cleanliness, the camera can also find blood that has been washed away or chemically broken apart.
Morgan's new imaging technique, which is currently confined to a laboratory setting, could soon see far more than just blood. By looking at specific wavelengths of light, he says it should be possible to take pictures of a person's fingerprints with the camera. The camera could then identify the owner of the fingerprints and even tell investigators which drugs or explosives that person recently handled.
"This is next week's 'CSI' tool," said Morgan. "Right now it's entirely proof-of- concept and we've only done a few validation tests, but it is very promising."