PARIS – Murder suspect Christian Nielsen has amended his plea to add “not criminally responsible by reason of insanity or mental disease or defect,” according to a filing in Oxford County Superior Court on Wednesday.

The former short-order cook from Newry pleaded not guilty to shooting and mutilating four people from the Black Bear Bed & Breakfast in Newry over Labor Day weekend last September while he lived there.

Nielsen, 32, was moved Tuesday from the Cumberland County Jail in Portland to Riverview Psychiatric Center in Augusta for mental tests.

The amended plea filed by attorney Ron Hoffman of Rumford is expected to be heard before Justice Robert E. Crowley.

Crowley is also expected to rule on Hoffman’s request that all evidence in the case be suppressed because it was obtained illegally and all statements Nielsen made to police on or about Sept. 4 be thrown out because they were not voluntary and he was not read his rights, according to a motion filed Tuesday.

“We believe he’s mentally ill, based on the crimes and also the subsequent stuff that’s happened since then,” Hoffman said.

Just days after his arrest, Nielsen struck a fellow Oxford County jail inmate in the head with a mop wringer and was moved to the Cumberland County Jail, which is better equipped for higher-security inmates.

In December, he was placed on a suicide watch after using a disposable razor to make cuts on his scalp that resembled the letter “X.”

And this spring, the 6-foot-tall inmate dropped from 158 pounds to 103, prompting Cumberland County Sheriff Mark Dion to secure permission from Justice Robert E. Crowley to force-feed Nielsen. He chose to begin eating again, so the sheriff didn’t have follow through on the court order.

Earlier this month, Nielsen was ordered to undergo a more extensive examination in a mental health facility for up to 60 days, but the exam was delayed until his physical condition improved.

Capt. Ernest Martin, administrator of the Oxford County Jail, said Nielsen was moved by the Oxford County Sheriff’s Office to the Augusta institution Tuesday.

“They’re going to look at his history,” Hoffman said, and the examination would determine Nielsen’s competency and any mental issues he might have.

The attorney also said if Nielsen is found criminally not responsible for the killings, he will be sent to the criminal division of a psychiatric facility, most likely Riverview.

“He would be treated as a mentally ill patient, not a criminal patient,” Hoffman said.

While there is a “very, very slight chance” that Nielsen could get released down the line if he is found criminally not responsible, it is more likely that he will spend the rest of his life at the facility, his attorney said.

Hoffman said he does not believe the change of plea will affect the trial, which is tentatively scheduled to take place in October.

The question of Nielsen’s sanity will be up to the jury to determine, unless he and the prosecutor come up with a prior agreement, he said.

Andrew Benson, assistant attorney general in the criminal division and prosecuting attorney in the case, is away from his office until Monday and was unavailable for comment.

Authorities say Nielsen confessed to shooting: James Whitehurst, 50, of Batesville, Ark., a guest at the inn, Sept. 1 in Upton, whose corpse was burned; Julie Bullard, 65, the inn’s owner, in her bed on Sept. 3; and Selby Bullard, 30, of Bethel, the owner’s daughter, and her friend Cindy Beatson, 43, of Bethel, on Sept. 4, when they showed up at the inn to check on Julie. The women’s bodies were dismembered.

Nielsen was arrested at the scene after calling his father to report the shootings, according to state police.

The Associated Press contributed to this report