BELFAST — Until the night police say he stabbed his mother to death, Jonathan T. Curtis had never been in legal trouble.

Witnesses, as well as psychological reports provided as evidence in Belfast Juvenile Court, described Curtis as a teen-ager who was basically a good kid, despite mood swings that veered from happiness to severe depression as he coursed through high school. He had no prior criminal record.

The witnesses speculated that a difficult family life turned Curtis from an honor student his freshman year to a homeless dropout sleeping in fields before the end of his junior year. Curtis had slashed his wrists eight months before he allegedly took his mother’s life.

Curtis was 17 when his mother was killed in the early morning hours of Aug. 20, 1994. Patricia Goguen, 34, died of multiple stab wounds from an attack in her apartment at 21 Union St. in Belfast. Her live-in boyfriend, Danny O’Brien, the couple’s 15-month-old son, Dakota, and Curtis’ 15-year-old girlfriend were at home the day of the killing.

Judge Bernard Staples conducted Tuesday’s hearing to determine whether Curtis should be tried for murder as a juvenile or as an adult. If convicted as a juvenile, Curtis could only be placed under state care until the age of 21. As an adult, he could receive up to life in prison.

A state psychologist testified that Curtis had “conduct disorder,” similar to that of a juvenile, but that he was aware of his actions and should be treated as an adult.

“It is my impression that Mr. Curtis had given up the ways of adolescence and was pursuing the path of adulthood,” testified Dr. Neil MacLean, the state’s chief forensic psychologist.

Curtis’ high school guidance counselor, Susan Murphy, had a different impression of the young man who turned 18 in January while incarcerated at the Maine Youth Center. Murphy testified that Curtis “was having a tough time as a youngster. … He was apathetic about living.”

The stabbing took place after Goguen, Curtis and his girlfriend, Samantha Heckler, had spent the evening drinking and smoking marijuana. Heckler testified that Curtis consumed eight cans of Old Milwaukee beer that night while his mother drank a fifth of Allen’s Coffee Brandy. Heckler had three beers. All three smoked a few “bowls” of marijuana, and Goguen also swallowed a handful of “speed” pills while the three were partying, Heckler said.

Speaking barely above a whisper and weeping often throughout her two hours on the stand, Heckler, now 16, said that during the three weeks she and Curtis lived with Goguen, she repeatedly subjected them to drunken harangues. Goguen was angry with her son for dropping out of school and for wanting to start a family with Heckler.

Heckler said she and Curtis went to bed at about 9 p.m. that Friday, but that an intoxicated Goguen kept bursting into their bedroom demanding that Curtis “come out and party.” The third time Goguen entered the room, Heckler testified, “She said she was going to bash my head into the window, that I was no good and that I had drug him down.”

Heckler said Curtis responded by pulling a knife from his book bag and “just went at her. He went towards her and was stabbing her.” She said that when she caught up to Curtis out in the street moments later, “he didn’t have a clue” as to what he had just done. “He was in shock.”

Curtis and Heckler immediately walked to the Belfast Police Station where he turned himself in, she said. “He said he was the guy who just stabbed his mother,” she testified.

In a videotaped confession recorded later that morning, Curtis recalled for state police detectives that “all I did was keep swinging” the knife.

During his cross-examination of Dr. MacLean, defense attorney Peter Mason pressed the state psychologist on his interpretation of a series of tests he administered to Curtis. MacLean insisted that despite findings of a “personality dysfunction” that was “usually associated with an adolescent,” Curtis’ decision to move out on his own and drop out of school was indicative of “pursuing a more adult avenue.”

MacLean suggested that Curtis’ type of personality disorder was “reticent to change,” and it would take more than three years to “affect change.”

Mason was critical of MacLean’s interpretation and indicated that his expert witness, Dr. Charles Robinson, reached a different conclusion when he subjected Curtis to similar tests. MacLean also was unable to explain why he failed to re-administer one critical test after his initial exam produced “invalid” results that differed from his diagnosis.

“I am somewhat perplexed as to why that is,” MacLean said. “I have a mixed bag here. I’m not sure why it is invalid, but in any event I maintain that it is.”

Testimony will resume on Wednesday morning. Referring to last month’s decision by Judge John Sheldon that Sheri Johnson, a 14-year-old who stabbed her great-aunt more than 106 times, be tried as a juvenile, Judge Staples instructed Assistant Attorney General Thomas Goodwin to call the head of the Maine Youth Center as a witness. Judge Staples said he needed to be aware of what forms of treatment would be available to Curtis, both within and outside of Maine, in the event he reached a similar decision.

“I want to know that,” Staples told Goodwin.