PORTLAND — A Superior Court judge today ruled that even though Chad Gurney mutilated Zoe Sarnacki’s corpse after killing her in 2009 and clearly suffered from a personality disorder, he was not delusional, knew what he was doing and even tried to cover up the crime.

Justice Roland Cole decided Gurney was guilty of murder and of arson in killing 18-year-old Sarnacki on May 25, 2009. Cole’s ruling comes two weeks after a bench trial in which Gurney admitted to the killing but claimed he was not guilty because of mental disease or defect.

No sentencing date has been set.

Cole evaluated the numerous conflicting psychological evaluations.

Some noted that a serious head injury Gurney received in a traffic crash in 2005 changed his personality and behavior, and that his effort to wean himself off painkillers contributed to his aggressive behavior. Evaluations after Sarnacki’s death said Gurney reported hearing voices and seeing signs in mundane things that others did not see. He said her decapitation and the fire he set were a purification ritual that would give her eternal life.

Cole was persuaded by Gurney’s behavior, and said the murder was a domestic violence homicide.

Gurney was upset that Sarnacki had been intimate with another man while he was out of town and disappointed that she would not travel with him to Thailand, Cole said. Gurney killed her, had sex with her corpse and decapitated her body. He showered and changed, then left the apartment at 463 Cumberland Ave. and purchased a container of gasoline. He poured it on the bed and around the apartment, then set a fire he hoped would cover up his crime.

Before he left, he grabbed his computer, an empty shotgun and his passport. He checked into an Old Orchard Beach motel and planned to fly to Thailand in a couple of days.

“I find that the defendant knew that his conduct carrying out the criminal acts of May 25, 2009, was wrong, that he was not psychotic on that date,” Cole said.

The recitation of Gurney’s attack on Sarnacki drew sobs from members of her extended family that attended today’s court appearance. Her parents did not attend.

“We’re just glad it’s over,” said her uncle, Tom Fasulo.

Gurney sat stoically as the verdict was read. Gurney’s family, however, his mother and sister among them, broke down crying as Cole concluded his verdict.

Gurney’s sister, Demarie Bateman, said afterward that she prays daily for Sarnacki and feels terrible for her family. Now they can start healing, she said.

“They have closure today,” Bateman said. “She’s in a better place and unfortunately, my brother is still here, but in a way, he’s dead to us.”

“He really isn’t a bad person,” Bateman said. ‘He just needs help. Hopefully, where he’s going, he gets help.”

9:50 a.m.

A judge has delivered a verdict of guilty in the trial of a Portland man who strangled his girlfriend, cut off her head and set her body afire.

During the trial, prosecutors and defense lawyers clashed over the mental state of 29-year-old Chad Gurney, who was using an insanity defense. The defense contends Gurney was delusional at the time of the killing, but the prosecutor contends Gurney was simply angry because his girlfriend had slept with someone else.

Neither side questioned that Gurney killed 18-year-old Zoe Sarnacki in his apartment on May 25, 2009.

Justice Roland Cole, who heard the case without a jury, delivered his verdict today in Cumberland County Superior Court.