Idaho college killings: Prosecutors dispute DNA could have been planted at murder scene

Idaho prosecutors responded to a suggestion from the defense that suspect Bryan Kohberger's DNA could have been planted at the scene of last year's quadruple murder, saying it does not support one of their requests for additional discovery.

In previous court filings, lawyers for Kohberger asked for more information on the genealogical analyses used to zero in on the suspect, attempting to cast doubt on the strength of investigators' evidence and whether it pointed irrefutably to just their client. The defense lawyer even questioned the investigators' objectivity.

The Latah County Prosecutor, leading the case against Kohberger, said in court filings Monday that none of the defense's arguments hold water as reasons to share the additional information.

"The State is at a loss as to how that theory supports a claim that the lGG information is material to the preparation of his defense," they wrote.

Investigative Genetic Genealogy (IGG) helped law enforcement eventually link Kohberger to the crime scene, after a more common DNA criminal profiling method, called a short tandem repeat analysis (STR), first found no match with the DNA left at the crime scene.

Prosecutors said the profile used in their IGG was informed by the same DNA as the STR analyses they performed, and they are already handing over information related to the STR analyses in discovery.

"If Defendant wishes to explore the theory that his DNA was planted on the Ka-Bar knife sheath, he is free to do so. But the family tree created by the FBI has no relevance to that theory," the prosecution wrote.

Kohberger's attorneys said last month they should get additional discovery on the genealogical "family tree" which helped lead authorities to their client.

The defense said in a June filing that Kohberger's DNA could have been planted -- put on the Ka-Bar sheath by someone other than him -- by someone throughout the investigation, for instance, which spanned "hundreds of members of law enforcement and apparently at least one lab the State refuses to name." The IGG process was "like a lineup where the government was already aware of who they wanted to target," they said, pointing to three additional males' DNA they say were found in and around the scene after the killings, and adding that "precisely how the police came to believe" they had identified the suspect's car as the kind Kohberger drove "is still unknown."

"The Defense is to guess whether the State focused its investigation on Mr. Kohberger via a bizarrely complex DNA tree experiment or through its faulty identification of the vehicle involved in this case," they wrote in the June filing.

In their filing Monday, the prosecution said that even if Kohberger's team wants to go down that road and claim that process was "rigged" -- it would be an irrelevant argument because they are not planning to present the genetic genealogy information at trial.

The prosecution said the IGG analysis was used to point them in the right direction -- but is a separate process from the ultimate STR DNA profile -- and they are not planning on using IGG at trial.

The prosecution also noted they have already handed over information related to the STR analyses.

The two analyses are distinct, they say -- the IGG was used "to develop a lead, not to demonstrate substantive evidence of guilt," while the STR analysis "is substantive evidence the State intends to use at trial to prove its accusations" against Kohberger, the prosecution writes.

They include an affidavit from the Idaho State Police Forensic Services Laboratory manager who notes the STR data and the data used in investigative genetic genealogy "cannot be directly compared."

Because they don't plan to use the IGG analyses at trial, the prosecution argued it wasn't relevant information to disclose. Anyone involved with those analyses wouldn't constitute a prosecution witness, thus making that defense argument inapplicable, they said.

"The IGG information is neither exculpatory nor material to guilt or punishment. The family tree built by the FBI merely pointed law enforcement to Defendant, and law enforcement followed that lead to develop the substantive evidence of guilt that was used for his arrest and that will be used at trial," the prosecution writes.

Responding to a June defense expert declaration in support of further discovery on the DNA analyses, the prosecution says that expert, who is also an attorney, should not "hijack" the court's role in determining evidence's relevance and admissibility, adding their declaration was a "poorly disguised legal brief" by a lawyer who is not on the case.

Prosecutors allege that in the early morning hours of Nov. 13, 2022, Kohberger, a criminology Ph.D. student at nearby Washington State University, broke into an off-campus home and stabbed to death four University of Idaho students: Ethan Chapin, 20; Madison Mogen, 21; Xana Kernodle, 20, and Kaylee Goncalves, 21.

After a six-week hunt, police zeroed in on Kohberger as a suspect, saying they tracked his white Hyundai Elantra, cellphone signal data, and recovering what authorities said was his DNA on a knife sheath found next to one of the victims' bodies.

That DNA evidence taken from the knife sheath at the crime scene "showed a statistical match" with a cheek swab taken directly from Bryan Kohberger after his arrest, authorities said in court filings.

Bryan Kohberger's attorneys pushed back on that analysis in several court filings, saying the "statistical probability is not an absolute," and pointing to what they called a "total lack of DNA evidence" from the victims in Kohberger's home or car.

Kohberger was arrested on Dec. 30, 2022, at his family's home in Pennsylvania, after driving cross-country to spend the holidays in Albrightsville.

He was indicted in May and charged with four counts of first-degree murder and one count of burglary. At his arraignment, he declined to offer a plea, so the judge entered a not-guilty plea on his behalf.

A trial in the quadruple homicide has been set for Oct. 2, though that could be delayed.