Police found blood on a handrail at the home of four Idaho student murder victims and more on a glove outside. 

The samples came from two unidentified but different men. Prosecutors say those samples shouldn’t come into play at trial if the defense intends to argue that they suggest a mystery man stabbed the undergrads to death and not the defendant.

Idaho prosecutors are asking a Boise judge to block Bryan Kohberger’s defense from arguing an “alternative perpetrator” theory unless he can first prove it’s relevant to the case under the state’s rules of evidence.

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Kohberger is accused of killing four University of Idaho students in a six-bedroom house on King Road, just steps away from campus. The victims were known to host parties, some of which resulted in police calls and bodycam video.

They were three housemates – Madison Mogen, 21, Kaylee Goncalves, 21, and Xana Kernodle, 20 – and Kernodle’s boyfriend, Ethan Chapin, 20, who lived at the Sigma Chi fraternity house about 200 yards away but was spending the night. All four had been killed by multiple stab wounds.

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Investigators have argued that the unidentified blood samples from two unknown males don’t matter as much as the knife sheath found under Mogen’s body. Prosecutors allege it had Kohberger’s DNA on the snap. She was killed next to Goncalves.

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“The State respectfully submits that the Defendant should be precluded from offering or arguing alternative perpetrator evidence without first meeting the relevance and admissibility thresholds of [Idaho Rules of Evidence] 401, 402 and 403,” Latah County Prosecuting Attorney Bill Thompson wrote in a court filing last week made public Tuesday.

Those rules govern the relevance and admissibility of evidence.

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Thompson cited an Idaho Supreme Court decision that found, “If the defendant proffers evidence which merely tends to mislead the jury that another person committed the crime, or the evidence is not relevant because it does not tend to make the defendant’s involvement more probable or less probable, then it is within the trial court’s discretion to find the evidence inadmissible.”

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“Mere inferences that another person could have committed the crime will most likely not be relevant.”

However, with the sources of the two blood samples in question, defense attorney Anne Taylor told Ada County Judge Steven Hippler at a hearing last month that it could mean Kohberger, 30, is not related to the crime at all.

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Edwina Elcox, a Boise-based defense attorney who is following the case, predicted the defense would use that evidence to “muddy the waters” and try and show reasonable doubt at trial.

Kohberger’s highly anticipated trial is scheduled to begin on Aug. 11.

He could face the death penalty if convicted.

Before he was granted a change of venue, Latah County Judge John Judge entered not guilty pleas on Kohberger’s behalf at his arraignment in May 2023.