LEWISTON – A brain scan of Christian Nielsen turned up no tumor, his attorney said.

That means Nielsen’s defense at trial next fall, if he goes to trial at all, would focus on his mental health at the time he allegedly killed four people.

Maine law allows a defendant to assert a psychiatric defense, in which he claims to be “not criminally responsible” for his actions even though he carried them out, as a result of “mental disease or defect.” Nielsen’s legal team would have to prove that he was not criminally responsible.

In Nielsen’s case, defense attorney Ron Hoffman said he expects to claim his client was suffering from mental illness at the time and didn’t have the capacity to appreciate the wrongful nature of his actions, should the jury decide he committed any criminal conduct. The jury also could find Nielsen “not guilty” if the state fails to prove beyond a reasonable doubt that Nielsen intentionally or knowingly killed three women and a man in Newry and Upton last year.

Nielsen had no apparent motive, has no history of violent behavior and no history of abuse, Hoffman said.

He said the results of an MRI (magnetic resonance imaging) procedure carried out last fall were negative for a brain tumor. That leaves in question the state of Nielsen’s sanity over the Labor Day weekend in 2006.

His attorneys got permission from the court to hire an expert to conduct a private mental evaluation before a state agency conducted its own examinations. The results of those evaluations remain sealed in a court file, Hoffman said. He should have access to them as soon as they are complete, he said.

Nielsen answered during a Cumberland County Jail intake interview that he had no history of mental illness and had never been admitted to a mental health facility.

But Hoffman said Nielsen had been treated at a psychiatric facility in New Hampshire when he was a juvenile. Records of that treatment are currently being sought. The facility has since changed names making it harder to access that information, Hoffman said.

He said it’s not surprising that Nielsen denied having been treated for mental illness. Nielsen was sent to Riverview Psychiatric Center in Augusta recently for a competency evaluation after he began exercising excessively and eating very little. The weight on his 6-foot frame had dropped from 158 pounds to 103 pounds.

When Hoffman asked Nielsen about his eating disorder, he denied having one. Hoffman said he pointed out to his client that even marathon runners should weigh considerably more than Nielsen.

“I’m eating,” Nielsen reportedly replied. “How do I have a problem with my weight?”

Hoffman said he expects to know within two months whether Nielsen has been found competent to stand trial, which is scheduled for October.

If he isn’t, the state has up to one year to try to make Nielsen competent to stand trial. His trial date would be pushed back because Nielsen would have to be competent in the months leading up to the trial to assist with his defense, Hoffman said. If the state were to fail to make Nielsen competent during that year, it would have to dismiss the charges, Hoffman said.

Nielsen has displayed other behavior since his arrest that raises questions about his mental competency, his attorney said.

He assaulted another inmate at Oxford County Jail, prompting officials to house him at Cumberland County Jail instead. There, he carved an “X” into his forehead using a razor, then apologized to guards.

Assistant Attorney General Andrew Benson said only Nielsen’s mental state at the time of the slayings is relevant to the merits of the case.

Both sides could agree that Nielsen should be committed involuntarily until he’s deemed safe to be released.

But Benson said he doesn’t see that happening.

“I think that’s extremely unlikely,” he said.