Bryan Kohberger, the man accused of murdering four University of Idaho students in 2022, appeared at a hearing in Idaho on Thursday as his lawyers attempt to eliminate the possibility of the death penalty if he is convicted.

Kohberger, who sat in court wearing a suit on Thursday, has been charged with four counts of first-degree murder and burglary for the deaths of Madison Mogen, 21; Kaylee Goncalves, 21; Xana Kernodle, 20; and Ethan Chapin, 20, who were stabbed to death in an off-campus residence in Moscow, Idaho, two years ago on 13 November 2022. He has pleaded not guilty.

At a hearing on Thursday morning, Ada county judge Steven Hippler heard oral arguments from both the county prosecutors and Kohberger’s defense team over capital punishment.

Idaho is one of the 27 states in the US that has the death penalty. The approved methods of execution in the state include lethal injection and, as of last year, execution by firing squad.

Prosecutors in Idaho issued their intention to seek the death penalty for Kohberger last year, as required by state law. In order to sentence a defendant to death after a murder conviction, the jury has to be unanimous.

In court documents, the prosecutors have argued that several aggravating factors exist in Kohberger’s case that they say could qualify for the crime of capital punishment under state law.

The factors they have asserted include that there are multiple victims, that the murders were “especially heinous, atrocious, or cruel”, that he exhibited “utter disregard for human life”, and that he exhibited a “a propensity to commit murder which will probably constitute a continuing threat to society”.

But Kohberger’s lawyers argue that the death penalty sentence ought to be removed from his case, calling it unconstitutional.

They argue, among other points, that the death penalty would violate Kohberger’s right to be free from cruel and unusual punishment, his right to due process, and that the death penalty goes against “contemporary standards of decency”.

His lawyers have also claimed that the criteria and standards for applying the death penalty are unclear and “unconstitutionally vague”, according to NBC News, and that Idaho’s requirement for a speedy trial makes it challenging for them to adequately prepare for a high-stakes death penalty case.

During the hearing on Thursday, Kohberger’s lawyers also argued that there is currently a shortage of lethal injection drugs in the US and in Idaho and that the state lacks effective means to execute an inmate.

“Idaho does not have a current means of executing anybody,” Anne Taylor, Kohberger’s public defender, said. “When somebody sits on death row and there’s no real means of executing them, that is dehumanizing to that person.

“It is anxiety. It is fear. it is the not knowing,” Taylor said, adding that the other method, firing squad, she believes is unconstitutional and has not been built yet in the state.

The prosecutors pushed back on the idea that Idaho does not have the means to put someone to death, saying that Idaho now has lethal injections available and that the methods could also change in the future.

“We just don’t know enough now, frankly, to spend the time and the effort debating what we don’t know in the future,” the prosecutor said.

The death penalty in Idaho has not been used since 2012 because the state has had trouble obtaining lethal injection drugs and then earlier this year, an execution was botched and delayed an execution when prison staff couldn’t find the man’s vein.

It is not clear when the judge will make a decision.

Kohberger, 29, a former criminal justice student at Washington State University, was arrested on 30 December 2022 at his parents’ house in Pennsylvania after weeks of investigation.

His DNA was matched to DNA found at the crime scene on a knife sheath and his cellphone data or surveillance video showed that him having visited the area at least a dozen times before the killings and that he traveled in the region that night.

Kohberger’s lawyers have said in court filings he was out for a drive that night, as they say he did often to hike and run, “and/or see the moon and stars”.

After he was arrested, Kohberger was extradited to Idaho and has pleaded not guilty to all of the charges.

Kohberger’s trial is set to begin in early August 2025 and jury selection is scheduled to start 30 July.

In September, a judge in Idaho moved the trial to Boise from Latah county after Kohberger’s attorneys argued, among other things, that he could not receive a fair trial in the courthouse in the local area where the killings happened.