Investigators found a knife sheath near one of the victims which contained the microscopic clue.
www.krem.com
Updated: 6:48 PM PST January 5, 2023
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In an 18-page affidavit of probable cause, investigators reported a knife sheath was found next to the body of Madison Mogen. On that sheath, Idaho's State Lab found a 'single source of male DNA,' which was labeled suspect profile. The sample was pulled from the button snap on the sheath.
"The reason DNA is so compelling is because it is a unique signature. Unless you have an identical twin, no one has your exact DNA," says CeCe Moore, Chief Genetic Genealogist for Parabon.
Moore pioneered the genetic techniques that have been used in solving hundreds of criminal cases, such as the Golden State Killer case in California (Parabon didn't work on that particular case).
The techniques can crack a case with only a tiny sample of DNA.
"Because technology has advanced so far, it is possible to just use a few skin cells in order to identify someone," Moore says. "That is true both for the traditional genetic forensic profile, that is what is court-admissible DNA evidence. It's also true for investigative genetic genealogy, we can work with the tiniest fragment of DNA, and that includes touch DNA.
Based on the affidavit in this case, it looks like touch DNA is what they had to work with. That's just skin cells."
Moore says we are always shedding our DNA wherever we go, in our epithelial or skin cells, saliva, and even hair without a root. That's why, she says, with the advance of technology in genetics it's nearly impossible for criminals to go uncaptured.
"So, in this case, it looks like they had to take that tiny amount of DNA and perform two separate lab analyses on that, because the crime lab creates that STR profile, the one that is court admissible. But a private lab has to create the SNIP- based genetic profile that's used for genetic genealogy.
And at this time, none of the crime labs have the capability to do that themselves. So it would have had to have been sent out. So clearly, even if it was a very small amount, there was enough to be able to do these two separate lab analyses, which is really interesting," Moore says.
Moore guesses, from her analysis of the affidavit, investigators zeroed in on Kohberger either because of a combination of the DNA evidence and technological evidence, like his type of car being seen near the King Road home numerous times, or that they "could have had good enough genetic genealogy matches that they were able to connect to both his mother's side of the family and his father's side of the family. And if they did that, it would have pointed right at him because he is the only son of that union."
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