University of Idaho student murders suspect Bryan Kohberger is now fighting for his life.

Prosecutors had 60 days since Kohberger's May 22 arraignment to inform the court and the defense that they planned to seek capital punishment.

They did so Monday in a court filing, alleging the 28-year-old "has exhibited a propensity to commit murder which will probably constitute a continuing threat to society."

BRYAN KOHBERGER CASE: STATE TO SEEK DEATH PENALTY AGAINST IDAHO MURDERS SUSPECT

Bryan Kohberger enters a courtroom

Defendant Bryan Kohberger enters the courtroom for a motion hearing regarding a gag order in Latah County District Court on June 9, 2023 in Moscow, Idaho. Kohberger is accused of killing four University of Idaho students in November 2022. (Zach Wilkinson-Pool/Getty Images)

"I'm not surprised," said Neama Rahmani, a former federal prosecutor and Los Angeles-based trial attorney. "This is one of the most heinous murders in Idaho state history."

Kohberger is accused of killing Madison Mogen, 21, Kaylee Goncalves, 21, Xana Kernodle, 20 and Ethan Chapin, also 20, in a 4 a.m. home invasion stabbing on Nov. 13, 2022.

Madison Mogen

Madison Mogen is one of the four students who were found stabbed to death in off-campus housing near the University of Idaho. (Jessie Frost Photography)

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The three young women lived together in a six-bedroom home just steps off campus of the University of Idaho in Moscow with two other housemates who were not targeted. Chapin was dating Kernodle and visiting for the night – just days before the students would have left for Thanksgiving break.

Kaylee Goncalves smiling in a white sweater.

Kaylee Goncalves, one of four University of Idaho students found murdered on Nov. 13 in a home near campus. (Facebook)

"There are many aggravating factors supporting the imposition of the death penalty, including multiple victims who were brutally and senselessly stabbed," Rahmani told Fox News Digital. "After the state botched the death penalty in the Lori Vallow case by not complying with its discovery obligations, I expect them to be very aggressive in this case."

In their notice of intent to seek the death penalty, prosecutors also alleged there were no "mitigating" factors to offset the "aggravating" ones Rahmani mentioned.

University of Idaho victim Xana Kernodle

University of Idaho student and stabbing victim Xana Kernodle in an undated photo. (Instagram @xanakernodle)

However, prosecutors can still seek a lesser penalty or pursue a plea deal despite the latest filing, experts say.

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"If there was a case to seek the death penalty, it is certainly this one," said Edwina Elcox, a Boise-based defense attorney who had previously represented Vallow. "The prosecutor has to comply with the statutory timelines, but could ultimately decide not to pursue the death penalty."

Idaho murders

Photo of Ethan Chapin, right, and Hunter Chapin, left, with their father Jim. The brothers were both members of the Sigma Chi fraternity, which has a house on the University of Idaho campus about 200 yards from the King Road home where the student stabbings took place. (Stacy Chapin)

"The gravity of the decision cannot be understated," Elcox told Fox News Digital. "But neither can the senseless murders of four young people with their whole lives ahead of them."

Kohberger is due back in court later Tuesday, as Judge John Judge is expected to hear arguments on several motions in the case. 

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Judge entered not guilty pleas to each charge of first-degree murder and another of felony burglary at the arraignment last month. Kohberger, speaking in January through his Pennsylvania defense attorney prior to waiving extradition to Idaho, said he was looking forward to being exonerated.

Bryan Kohberger's WSU portrait next to his victims

Bryan Kohberger and his alleged victims, clockwise from top left, Madison Mogen, Ethan Chapin, Xana Kernodle and Kaylee Goncalves. (WSU/Instagram)

The trial has been scheduled to begin on Oct. 2 and could take up to six weeks.

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Kohberger was studying for a Ph.D. in criminology at the neighboring Washington State University, less than 10 miles from the crime scene. The school cut ties with him after his arrest.

He has a master's degree in criminal justice from DeSales University in Pennsylvania.