OSHAWA, ONT. -- A man accused of murdering a woman and two of her children east of Toronto argued Monday that he was mentally "inanimate" at the time and lacked the criminal intent required to be found guilty in the case.

Cory Fenn has pleaded not guilty to three counts of second-degree murder for the deaths of Krassimira Pejcinovski, 39, her 13-year-old daughter, Venellia, and her 15-year-old son, Roy.

In closing arguments Monday, Fenn -- who is representing himself -- said he was like "the walking dead" at the time of the killings three years ago.

"I was inanimate," Fenn told an Oshawa, Ont., courtroom.

"The mental element was not there," he said. "It's like the Wizard of Oz going down the path, 'if I only had a brain' -- I didn't have one, guys."

"Your point is how can you have the mental element if you didn't have a brain?" asked Justice Howard Leibovich, who has been hearing the case.

"Right," Fenn said.

The 33-year-old Fenn did not call a defence in the case. He also fired his defence lawyer, but she was appointed by the court to help with his closing arguments. Fenn interrupted her submissions several times on Monday.

"This is torture," he said, before the judge explained that the lawyer was helping Fenn's defence. Fenn lay down in the prisoner box shortly afterward.

Last week, the Crown said Fenn killed Krassimira Pejcinovski in a rage after she broke up with him. The prosecution argued Fenn then killed her two children because they were related to her.

Court heard Pejcinovski was found stabbed to death on March 14, 2018, her body hidden by garbage and tires in the garage of her Ajax, Ont., home. Her daughter was found stabbed to death in the basement and her son found strangled next to her bed.

Fenn told a detective the day after the bodies were discovered he had "cocaine psychosis" and would never hurt Pejcinovski otherwise.

Crown attorney Mike Newell argued last week that Fenn knew exactly what he was doing and was not in a state of psychosis due to cocaine.

Mary Cremer, the lawyer appointed to help Fenn, said she agreed with the Crown that they had proved beyond a reasonable doubt that Fenn committed the physical act of killing three members of one family.

"The sole issue before this court is this: is there any evidence of intoxication affecting Mr. Fenn's mindset at the time of the deaths?" Cremer said.

She said there was ample evidence that Fenn was a "heavy" cocaine user and that he and Pejcinovski did lines of cocaine that night in the basement of Pejcinovski's home, which was where he lived.

Cremer pointed out there is no reliable timeline for the killings of Pejcinovski and her son.

Court heard Pejcinovski's daughter died some time between 10:38 a.m. and 10:48 a.m. on March 14, 2018, before Fenn fled after being confronted by Pejcinovski's boss, who came to the home looking for her employee.

Cremer said Fenn did not have the requisite state of mind to commit murder due to his extensive use of cocaine, rendering him in a psychotic state at the time.

Cocaine psychosis was the only way to explain the killings, she argued.

"The evidence here points to lack of intent on part of Mr. Fenn as caused by an advanced state of intoxication," Cremer said.

"At a minimum, your honour should find him not guilty of second-degree murder and all the evidence points to three counts of very tragic manslaughter."

The judge is expected to deliver a decision in the case on Jan. 21, 2022.

This report by The Canadian Press was first published Oct. 25, 2021.