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If a person’s DNA is found at a crime scene, that person had to have been in that room, jurors might assume. But that assumption might well be false, a recent University of Indianapolis study that started as a class project indicates.
With forensic science kits growing increasingly sensitive, samples may not only contain DNA from individuals who were actually at the scene or, say, personally handled a weapon. They also may include genetic samples from people with whom those individuals had contact, the study found.
This result suggests that investigators and jurors need to proceed with caution with “touch” DNA, small samples of material such as skin cells collected from a crime scene, the study’s authors say.In the past, scientists needed to have hair or bodily fluids to derive DNA. But the advent of touch DNA allows them to build a profile from just a few cells.
“There’s no nevers and no always in all of science. … Forensic DNA is a very, very important tool, but it is subject to interpretation just like the other types of evidence that are presented,” said Krista Latham, a University of Indianapolis associate professor and director of the school’s molecular anthropology laboratory, in whose class the work originated. “This solidifies that this is good science, but it also emphasizes that there is interpretation that comes with this science.”
Read full, original post: CSI UIndy: Study shows secondary DNA can show up at crime scenes