Bryan Kohberger Can't Use Insanity as a Defense in Idaho Murders

Bryan Kohberger, the suspected killer accused in the University of Idaho murders, will be unable to plead not guilty by insanity due to state law, according to one former federal prosecutor.

"Idaho is a state without a formal insanity defense. That is, state law does not allow a not guilty by reason of insanity verdict or result in a felony criminal case," Michael McAuliffe, a former federal prosecutor and elected state attorney told Newsweek on Thursday.

According to the American Psychological Association, Idaho's legislature repealed the state's insanity defense in 1982. However, the court may use expert evidence to consider mental illness as a factor in sentencing.

On December 30, Kohberger was arrested at his parent's home in Albrightsville, Pennsylvania, in connection to the fatal stabbings of four University of Idaho students, Kaylee Goncalves, Ethan Chapin, Xana Kernodle and Madison Mogen, that occurred in the early morning hours of November 13.

Before being extradited to Idaho, Kohberger's lawyer in Pennsylvania said in a statement that his client was looking to be "exonerated" of the charges filed against him, which include four counts of first-degree murder.

"Depending on the final charges, the state will have to prove the defendant possessed the required intent in order to obtain a conviction, particularly for first degree murder. However, the facts appear to show the killer engaged in a methodical, deliberate plan to stab four people to death and evaded capture. Those facts don't indicate a lack of criminal intent," McAuliffe told Newsweek.

Meanwhile, forensic psychiatrist and trial expert witness, Carole Lieberman, also told Newsweek that "Idaho abolished the Insanity Defense. So, his attorney could not try to have him found Not Guilty by Reason of Insanity."

Lieberman added: "However, Idaho courts do allow a defendant to present expert psychiatric testimony about any mental conditions that may have interfered with his ability to have formed the intent to kill, or to understand the nature of his crime, or to know whether it was right or wrong at the time."

On Thursday, the probable cause affidavit used to arrest Kohberger was released and revealed new evidence of the crime.

The affidavit revealed how Kohberger allegedly surveilled the 1122 King Road residence on numerous occasions and even included a description of a male that a surviving roommate saw in the home on the night of the murders. However, the affidavit does not reveal a motive for the crimes and why the four students were killed.

Additionally, investigators were able to build a DNA profile linking Kohberger to the crime by finding a "single source of male DNA" on a knife sheath found at the crime scene and comparing it to DNA recovered from the trash at his parent's home. The affidavit also included evidence surrounding Kohberger's cellphone number and how it was recorded using cellular towers near the off-campus residence where the murders occurred, at least 12 times prior to November 13.