Bryan Kohberger's DNA on Knife Sheath Is 'Surefire' Evidence—Criminologist

Bryan Kohberger's DNA on a knife sheath found at the home where four University of Idaho students were murdered is "surefire" evidence against him, according to a criminologist.

Kohberger, 28, is accused of breaking into a rental home near the university campus in the early hours of November 13 and fatally stabbing Kaylee Goncalves, 21, Madison Mogen, 21, Xana Kernodle, 20, and Ethan Chapin, 20. At the time, he was a graduate student studying criminology at nearby Washington State University.

He was arrested at his parents' home in Pennsylvania in late December. Police pieced together DNA evidence, cellphone data and surveillance video to connect Kohberger to the crime, according to a probable cause affidavit unsealed in early January.

After being indicted by a grand injury last week, Kohberger declined to enter pleas during his arraignment on Monday. His defense attorney, Anne Taylor, told the judge that they were going to "stand silent" at this time. Not guilty pleas to four counts of first-degree murder and one of burglary were entered on Kohberger's behalf.

Kohberger's trial is currently scheduled to begin on October 2. Latah County Prosecutor Bill Thompson has 60 days from the arraignment to inform the court whether he will seek the death penalty in the case.

According to criminologist Debbie Goodman, the DNA evidence in the case is strong and believes it will be a focus of Kohberger's trial.

"Indeed, this is surefire evidence," she said during an appearance on NewsNation.

Traces of DNA from a "lone male" were on the button of a leather knife sheath found in the home where the victims were killed, according to the affidavit written by Brett Payne, a police corporal in Moscow.

Investigators later closely matched the DNA on the sheath to DNA found in trash taken from Kohberger's parents' home in Pennsylvania.

"We have in our field something very, very important when it comes to murder cases such as this. It's genetic genealogy," Goodman said.

"So what that means is each of us has our own composition compilation of saliva, fluid, blood, print, and the fact that we have this knife sheath... we are now able to take that and our investigators have done a tremendous job here, local, state and federal, whereby they have aligned the composition of what's on that knife sheath with trash that had been discarded in the family home of the Kohbergers and there is alignment, so that I believe as a criminologist is going to be a central feature in this case."

However, Duncan Levin, a criminal defense attorney, previously told Newsweek that the evidence that led to Kohberger's arrest isn't indisputable.

The DNA on the knife sheath "is not irrefutable proof of anything since it does not put him in the house at the time of the murders," Levin said.

DNA and cellphone evidence "can be very technical and subject to cross-examination," he added.