PORTLAND – In what’s shaping up to be a “head case,” a judge said a man accused of murdering four people is allowed to undergo a brain scan for a possible tumor.

Cumberland County Superior Court Justice Robert Crowley also ruled Wednesday that Christian C. Nielsen, 31, of Newry must submit to a psychiatric examination sought by prosecutors.

Appearing in court wearing bright yellow jail-issued shirt and pants and orange sneakers, Nielsen told the judge he understood each of the four murder counts against him, then he pleaded not guilty to all four.

Prosecutors had argued they should be allowed to schedule Nielsen for an independent psychiatric examination, believing he is likely to mount a defense based on his mental health at the time of the shooting deaths on Labor Day weekend in Newry and Upton.

The case is “almost certainly never going to be tried as a ‘whodunit,'” Assistant Attorney General Andrew Benson told the judge. Instead, it’s likely to be “some kind of head case.”

Crowley allowed the exam, but only after giving Nielsen a month to let his own medical expert assess his mental health.

By Nov. 15, prosecutors said they are likely to have completed their investigation and would share their findings with defense attorneys. After that date, they can schedule an exam for Nielsen.

Defense attorney Margot Joly of Wilton had argued against the independent exam, saying it would unconstitutionally force Nielsen to possibly make self-incriminating statements that might be used against him at trial.

Benson said the circumstances surrounding the case – Nielsen is accused of killing, then dismembering three of the bodies and burning the fourth – is cause enough to compel him to be examined. He said it’s important to have the exam done as soon after Nielsen’s arrest as possible.

Defense lawyers haven’t said whether they intend to offer an insanity defense or claim that an “abnormal condition of mind” might have contributed to Nielsen’s actions.

Unless they do, Crowley said the results of the mental health examination will remain sealed in court documents. He left it up to attorneys on both sides to decide if Nielsen’s attorneys should be present during the exam.

Ron Hoffman of Rumford, also representing Nielsen on Wednesday, said his client had been experiencing problems with confusion, was unable to concentrate and had difficulty reading. Past medical and counseling records indicted possible neurological problems, Hoffman said, adding that Nielsen had visited a psychiatrist and had undergone therapy earlier. Whether those issues would become part of the case, Hoffman said it was too early to tell.

Crowley ruled Nielsen was allowed to have an MRI, a process that takes pictures of brain tissue.

Defense attorneys are considering a possible insanity defense, Hoffman said after the hearing.

If they do, Benson said the defense would have the burden of proving to a jury that Nielsen was insane at the time of the killings. Otherwise, it’s the state’s burden to prove guilt beyond a reasonable doubt.

In court Wednesday, Nielsen was somber, Hoffman said. “He did seem a little confused, a little overwhelmed by the whole process.”

Nielsen is being held without bail at the Cumberland County Jail where he was transferred after allegedly assaulting an Oxford County Jail inmate after his arrest.

He is accused of killing James Whitehurst, 50, of Batesville, Ark., a guest at the Black Bear Bed & Breakfast on Sept. 1 in Upton; inn owner Julie Bullard, 65, on Sept. 3 at the inn in Newry; Bullard’s daughter, Selby, 30, of Newry and her friend, Cynthia Beatson, 43, of Bethel, on Sept. 4 at the inn. Nielsen, a cook at a Bethel inn at the time, was living at the inn and was taken into custody there Sept. 4 after his stepmother told police she saw a woman’s body outside.

Beatson’s family, including her husband and mother, attended the arraignment and hearings on Wednesday. They declined to speak to reporters.

Crowley said the case should go to trial in October, 2007. He allowed lawyers on both sides to file motions over the next four months. In all, the arraignment and hearings lasted less than half an hour.