(CNN) — It’s been a tough week for Bryan Kohberger’s defense team.

Defense lawyers for Kohberger, the 30-year-old accused of killing four University of Idaho students in their Moscow, Idaho, home in November 2022, had long suggested the “alternate perpetrator” theory – the idea that someone else killed the students.

But on Thursday, Judge Steven Hippler dealt a crushing blow to the defense, denying their request to identify specific alternate perpetrators before the jury. Idaho law requires the “alternate perpetrator” theory to be approved by a judge before atrial begins.

The defense offered four individuals as alternate perpetrators, according to the judge’s order, of which portions were redacted. The defense’s motion is sealed and not open to the public. The judge ruled the “defendant’s offer of proof can give rise to only wild speculation that it is possible any one of these four individuals could have committed the crimes,” which does not meet the requirements of state law.

“Nothing links these individuals to the homicides or otherwise gives rise to a reasonable inference that they committed the crime,” Hippler said in his ruling. “Indeed, it would take nothing short of rank speculation by the jury to make such a finding.”

The judge also rejected a bid from Kohberger’s defense team to delay the trial, slated to start August 11, saying the defense has not shown “there is good cause” to move back the trial start date. The trial has already gone through numerous delays due to disputes about evidence and witnesses, as well as a change of venue from Latah County to the state capital of Boise.

Lead defense attorney Anne Taylor argued in court last week the “challenges and difficulties” over the last two and a half years have made it so the defense team is still not ready to go to trial.

The blow to Kohberger’s defense comes after Hippler previously ruled he also cannot present an alibi defense – since no one can vouch for where he was during the time of the killings.

His defense team has said he was driving alone in the early morning hours of November 13, “as he often did to hike and run and/or see the moon and stars,” when the students were stabbed.

Kohberger – on whose behalf a not guilty plea was entered – could face the death penalty if convicted of the quadruple murders.

Here’s more of what we know about the “alternate perpetrator” theory – and where Kohberger’s defense team can go now as the options to defend their client continue dwindling.

Defense hoped to pin killings on one of 4 possible alternate perpetrators

The judge’s ruling says the defense suggested four possible alternate perpetrators of the murders, each of whom had some connection to or interaction with the victims in the days before they were fatally stabbed.

Three of the alternate suspects proposed by the defense were “each socially connected to one or more of the victims, interacted with one or more of the victims at social events in the hours prior to the homicide, lived within walking distance of the crime scene and were familiar with the layout of the victims’ home from prior social events,” said Hippler.

But the proposed perpetrators’ opportunity to commit the crime is “an opportunity shared by dozens of others in the victims’ social circles,” said the judge, adding, “there is no compelling evidence that any of them had motive to kill the victims - much less physically harm them - or means to do so.”

A fourth possible alternate perpetrator did not know the victims but had noticed one of them shopping at a store five weeks before the killings, according to the ruling. The moment was captured by surveillance footage.

“He followed her briefly out the exit of the store while considering approaching her to talk,” said Hippler. “He turned away before ever speaking to her.”

The suggested alternate perpetrators have all cooperated with law enforcement, providing DNA samples and fingerprints, the judge’s ruling said. Lab reports have excluded their DNA from samples taken from the crime scene, according to Hippler.

Alternate suspect theory has been front and center for defense

The “alternate perpetrator” has been one of several tracks the defense has highlighted as the trial approaches. During a pivotal pre-trial hearing in April, the defense announced it had received a tip of an alternate suspect, which they were taking very seriously and were investigating.

In May, Hippler said during the final pre-trial hearing he had received the defendant’s proffer or offer on an alternate perpetrator.

At that time, the judge said he would be sealing the paperwork but wanted additional information, asking for actual evidence of an alternate perpetrator rather than just allegations. He also wanted the defense to show how they believed what they were offering was admissible.

Now, in the court’s final order, while the defense may cross-examine law enforcement on investigating and ruling out other leads, they are not permitted to ask about specific individuals as potential alternate perpetrators.

Judge also denied Kohberger’s alibi

In another blow for the defense, Judge Hippler previously ruled that Kohberger cannot have an official alibi defense.

In August 2023, prosecutors told the court that Kohberger’s alibi was only that he was out driving around the night of the killings, and that he had not complied with Idaho’s alibi statute – which specifically requires him to provide names of witnesses to be called to support the alibi, along with their addresses. They said it was now too late to do so.

Since 2023, the defense has continued to push to use an alibi defense, saying the alibi may emerge from cross-examination or expert testimony about Kohberger’s cell phone tower data. The court, however, has continually told the defense they have to comply with the specific requirements of the statue.

During a motion hearing in April, the alibi defense was argued again. Prosecutors renewed their position that the defense can only say Kohberger was out driving around that night and the time his phone was turned off “coincided with the time of the murders.”

They pointed out the only person who can testify to Kohberger’s alibi is the defendant himself. Taylor, Kohberger’s lead attorney, emphasized her client has a right to remain silent.

Hippler then asked Taylor, “if not Kohberger … who is going to say he was driving around looking at the stars?”

The judge ruled the defense expert could show Kohberger was at a certain place until 2:50 a.m. on November 13, 2022, but that no alibi witness would be able to testify, and there would not be an alibi instruction given to the jury.

He also ruled the defense should immediately notify the court if it comes across evidence that supports an alibi. The defense hasn’t filed any motions related to the alibi since that April court decision.

Defense can turn to reasonable doubt

Unable to present an official alibi or suggest specific alternate perpetrators of the killings, the defense will likely focus on raising reasonable doubt that Kohberger committed the crimes.

During the cross-examination of every witness, the defense will likely work to show that Kohberger had no connection to the crime scene and no connection to the victims. They will also try to raise reasonable doubt during cross-examination of prosecution experts testifying about surveillance video allegedly of Kohberger’s car driving to Moscow in the months before the killings and during the early morning hours of the day the students were found dead.

The defense will likely try to discredit any cell phone tower data used to show the location of Kohberger’s phone on the night of the killings, as well as surveillance video from businesses in the area.

The defense has an expert of their own who will argue that Kohberger’s phone data shows he was outside the area at the time of the killings.

UnidentifiedDNA from blood found on a handrail inside the home could also be helpful to the defense, to further raise doubt that Kohberger was the killer and suggest investigators did not fully do their job.

Cross-examination of the victims’ two surviving roommates will likely be aggressive, especially of Dylan Mortensen. Mortensen told police she saw a masked man with “bushy eyebrows” and wearing all black in their home the night of the killings. Kohberger’s defense have painted Mortensen as an unreliable witness whose recollection of the night has been muddied by intoxication and post-event media exposure.

Both sides agreed they would not focus on investigative genetic genealogy, the technique that led to the identification of Kohberger as a potential suspect.

But in court filings, defense lawyers have floated the idea that the knife sheath found in the Moscow home could have been planted by the real killer. A single source of male DNA on the sheath, found next to the body of Maddie Mogan, was determined to be a “statistical match” to Kohberger.

And although Kohberger has a right to remain silent, he could take the stand himself – testifying in his own defense to explain the many unanswered questions around the case.

The-CNN-Wire
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