Attorneys in the murder case against James Pak of Biddeford have filed arguments that conflict over whether psychological reports show he is mentally competent to stand trial.

Pak, 77, has pleaded not guilty by reason of insanity to two counts of murder in the deaths of Derrick Thompson, 19, and Alivia Welch, 18, and other charges related to the shootings on Dec. 29, 2012, in the apartment that he rented to Thompson and his mother.

Pak’s attorney, Joel Vincent, argued in a brief filed Thursday in York County Superior Court in Alfred that Pak’s diminished memory makes him unfit to be tried for murder.

Police say Pak killed Thompson and Welch and wounded Thompson’s mother, Susan Johnson, 46, after a dispute over parking. Johnson called 911 after the shootings.

Police had been called to the apartment earlier that day, but left after deciding the dispute was under control, just minutes before Pak allegedly shot the three.

In his 21-page brief, Vincent said Pak’s “lapses in memory and recall support all the evaluators’ testing data and observations that the defendant has significant deficits in working memory skills, recall, verbal comprehension and the ability to follow directions. In sum, counsel argued that there has been no demonstration that Mr. Pak can meaningfully cooperate in his defense at this time.”

Assistant Attorney General Leane Zainea, who is prosecuting Pak, argued in a brief filed Sept. 17 that while the three psychologists who examined Pak determined that he has some cognitive limitations, all of them agreed that Pak understands the charges against him, the motivation for his actions and the important aspects of a legal defense.

“While the defendant may not possess the skills generally associated with those familiar with the criminal court process, he has repeatedly demonstrated he knows he is facing very serious charges, he has identified his attorneys and their importance in his representation, he understands the roles of the judge, prosecutor and jury and he has been able to recall and articulate details surrounding the criminal conduct,” Zainea wrote.

Justice John O’Neil Jr. who heard testimony from the psychologists at hearings in February and May, has indicated that he will rule on Pak’s competency after weighing both sides’ arguments.

Unless O’Neil finds one psychologist’s testimony more compelling than another’s, he will have to weigh conflicting opinions.

Psychologist Kerry Drach testified that Pak showed signs of possible dementia, did not seem to understand the gravity of the charges, and had limited ability to grasp complex court proceedings.

But Drach said his exams of Pak in 2013 were inconclusive. He recommended more tests, to assess Pak’s competency and whether he suffers from dementia.

The second psychologist, Robert Riley, testified that he examined Pak twice in 2014 and found him competent to stand trial and showing no signs of dementia.

The third psychologist, Melvyn Attfield, testified that he interviewed Pak four times at the York County Jail in Alfred and disagreed with Riley’s conclusions. Attfield, who was hired by Pak’s attorneys, said he found Pak was mentally impaired and had only the equivalent of a first-grade reading level.

Under the legal standard for competency in Maine, Pak must understand the charges and proceedings against him, comprehend how those charges relate to him, and be able to cooperate with his lawyers in a rational and reasonable manner.

The case drew increased attention because Thompson, Welch and Johnson were shot just minutes after Biddeford police left the apartment. Court documents say Pak waited for police to leave, got a gun, opened the door to the apartment and said: “I am going to shoot you. I am going to shoot you all.”

He shot Johnson first, then Thompson, then Welch, court documents say.

The two teenagers were dead by the time emergency responders arrived.