No longer destroy DNA evidence
New technology can distinguish between animal and human blood
Science and Technology Daily, Beijing, December 13th (Reporter Zhang Mengran) British "Communication·Chemistry" magazine recently published a new blood analysis technology. For the first time, a team of American scientists used Fourier transform attenuated total reflection infrared spectroscopy (ATR FT-IR) Combined with statistical analysis, a new model was established, and then a non-destructive technology that can distinguish human blood from 11 animal blood was reported.
This technology can be used to quickly determine whether bloodstains found at crime scenes are from humans.
Blood stains are one of the most important sources of DNA evidence, but current blood tests generally destroy samples and DNA evidence.
These tests will also provide false-positive results—reporting human blood in the absence of human blood.
In view of this, the reliable and non-destructive distinction between human blood and animal blood is very necessary for forensic forensics, especially in hit and run cases where the suspect may claim that the incident is related to animals rather than people.
Scientist Igor Ledniff of the State University of New York at Albany and his colleagues tried to combine Fourier transform attenuated total reflection infrared spectroscopy with statistical analysis to distinguish human blood from animal blood.
ATR FT-IR has extraordinary advantages in non-destructive testing and surface information acquisition. The research team used blood samples of humans, cats, dogs, rabbits, horses, cattle, pigs, possums, and raccoons to establish statistical models, and used deer, Blood samples of moose and ferrets validated these models.
The research team also selected common household pets, human food animals, or animals that may be involved in wild crime or hit-and-run incidents.
When the animal blood samples of the training data set were used to verify the model, there was 1 misclassification in 290 verifications; however, when the blood samples of deer, moose, and ferret were used for model verification, no misclassification occurred at all.
Bloodstain analysis is one of the important contents of on-site reconstruction technology.
The analyst will apply the principles and methods of biology and physics to study the bloodstain formation mechanism through the inspection of the bloodstain left on the scene, determine the bleeding site, the amount of bleeding, and the process of committing the crime, and can also obtain the movement status of related people and objects after the bleeding , In order to confirm whether the statements of all parties are true.
The research team said that considering that some ATR FT-IR spectrometers are currently portable, this technology will be used for the analysis of crime scenes.
Editor-in-chief
Through the detection of DNA in the blood, it has been possible to achieve some things that were previously unimaginable. For example, the detection of ctDNA in the blood can realize early screening of many common cancers. But blood DNA testing is not as easy as everyone thinks, especially in some complicated scenarios. At a crime scene, distinguishing between animal bloodstains and human bloodstains and obtaining accurate DNA results are seemingly simple things, but in reality they are full of challenges. The above research gives hope to the solution of this problem.