On December 30, criminology student Bryan Kohberger was arrested for the murders of four University of Idaho students in Moscow, Idaho. While authorities did not disclose the nature of the link between Kohberger and his alleged victims, the suspect was reportedly tied to the crime through DNA evidence.
As per Fox, Kohberger was fascinated with DNA testing, as he reportedly expressed an interest in his ancestral history. In an interview with the New York Post, a neighbor of Bryan Kohberger's, who chose to remain anonymous, said that the suspect reportedly expressed great curiosity regarding his ancestry, prompting him to send his DNA for genetic testing.
The neighbor said that Kohberger claimed to have German ancestry.
“He talked about his ancestors. He had some sort of DNA test. I don’t know how he got to that point. … It was just interesting to him."
The Daily Beast reported that it was ultimately DNA samples that led authorities to Bryan Kohberger. Along with forensic evidence, investigators probed surveillance footage and phone data records while creating a case against Kohberger. As per Fox, while Kohberger provided DNA for genetic testing, it was not likely that these samples were used in the case.
The use of genetic genealogy in the case against Bryan Kohberger
As per NPR, after Idaho authorities began suspecting Bryan Kohberger in the Idaho slayings, Pennsylvania officials assisted the investigation by collecting DNA samples from the suspect's home in Albrightsville. It was here that he was ultimately arrested in a pre-dawn raid.
The affidavit stated that the DNA sample discovered in Bryan Kohberger's trash matched the evidence found at the scene, which purportedly belonged to the suspect's father.
The affidavit read:
"At least 99.9998% of the male population would be expected to be excluded from the possibility of being the suspect's biological father."
The authorities used a DNA analysis tool, genetic genealogy, to trace the sample back to the suspect. CeCe Moore, the chief genetic genealogist at Parabon NanoLabs, explained how the analysis tool worked to Fox reporters.
"Typically, you're going to be building trees for dozens or two dozen of these matches, trying to see how they all connect. Are there patterns? Are there any intersections between these family trees?"
Pete Yachmetz, a security consultant and former FBI agent discussed the role of the DNA evidence while talking to New York Post reporters.
“What most likely happened is that the crime scene was a mess and there was DNA evidence left all over the place. So what they did was retrieved all the DNA evidence they could and analyzed it"
According to Yahoo, the Idaho State Lab identified Kohberger's DNA on a knife sheath that was discovered at the scene of the crime. The sheath is believed to have been used to carry the blade that the suspect used to stab his victims multiple times.