Forensic tech quickly determines if bloodstains are human
When a car hits something crossing the road in a dark, rural setting, it can occasionally be difficult for the driver to later say if it was a person or an animal – that, or they may just lie and say it was the latter. A new blood-analyzing device, however, could tell the difference on the spot.
"Most current techniques used for discrimination between human and animal blood cannot be done at the crime scene and also result in destruction of the sample," says the University at Albany's Prof. Igor Lednev. "We instead can offer a non-destructive way to test traces of blood left behind on a suspect’s car bumper that will answer the question of its origin immediately."
That method utilizes attenuated total reflection Fourier transform-infrared (ATR FT-IR) spectroscopy, which is related to the more commonly heard-of Raman spectroscopy. The latter technique begins with laser light being shone onto a sample. The molecules in that material vibrate in response, scattering the light in a unique manner. Therefore, by analyzing that scattered light, it's possible to ascertain which telltale chemicals are present in the sample.
ATR FT-IR is similar, although it's based on how molecules absorb light.
Working with doctoral chemistry student Ewelina Mistek-Morabito, Lednev used the technology to analyze 15 human dry blood samples, along with a total of 89 cat, dog, rabbit, horse, cow, pig, opossum and raccoon blood samples. When the data was analyzed using software that had been trained to recognize the ATR FT-IR signature of human blood, the scientists were able to differentiate between the human and non-human samples with 100-percent accuracy.
Lednev and Mistek-Morabito are now working with the New York State Police Crime Lab System, to incorporate the technology into a portable handheld device that could be used in criminal investigations. We're told that although the setup currently doesn't identify which animal species a sample came from, that may change as it's developed further.
The study is described in a paper that was recently published in the journal Communications Chemistry.