DNA from the cheek swab of the man charged with the slaying of four Idaho university students last year has been found to be a “statistical match” to that found on the knife sheath at the crime scene, according to a new court filing.
Bryan Kohberger, 28, is charged with killing Ethan Chapin, 20, Xana Kernodle, 20, Kaylee Goncalves, 21, and Madison “Maddie” Mogen, 21, in the early hours of 13 November 2022.
A new court filing by Latah County prosecutors revealed the details to the public for the first time, shedding light on the investigative methods used by the FBI to zero in on the prime suspect in the case.
A police affidavit previously connected Mr Kohberger’s DNA with the DNA found on the knife sheath retrieved from the scene of the crime.
It has been revealed that a short tandem repeat (STR) was developed using the evidence found on the knife sheath. The process involved looking at 20 regions within human DNA, allowing law enforcement to make a direct comparison between two STR DNA profiles.
“A traditional STR DNA comparison was done between the STR profile found on the Ka-Bar knife sheath and Defendant’s DNA. The comparison showed a statistical match,” the court filing said.
The new filing said that a matching STR profile makes it more likely that the suspect is connected to the crime weapon.
“The STR profile is at least 5.37 octillion times more likely to be seen if the defendant is the source than if an unrelated individual randomly selected from the general population is the source,” the filing stated.
Additionally, the documents provide details of a protective order sealing the development of the DNA profile and all associated documentation concerning the construction of the genealogical family tree.
It added that the sheath was found “partially under Madison’s body and the comforter on the bed”.
Investigators were able to trace the DNA evidence to Mr Kohberger by matching it to DNA found on trash recovered from his family home in Albrightsville, Pennsylvania.
The 28-year-old criminology PhD student faces life in prison or the death penalty if found guilty.
Mr Kohberger is being held in the Latah County Jail in Moscow, Idaho, on four counts of first-degree murder and one burglary charge. He is set to go on trial on 2 October.
