A Fort Saskatchewan, Alta., man accused of murdering his infant son should be convicted of manslaughter, Crown prosecutors suggested in court Friday.

Closing arguments for the trial of Damien Starrett, 33, were delivered Friday morning at the Court of Queen's Bench in Edmonton.

He is charged with second-degree murder and assault after attacking his two children, aged one and five respectively, in November 2019. His infant son, Ares, later died in hospital due to blunt force head trauma.

On Friday, however, Crown prosecutor Sandra Christensen-Moore suggested Starrett should instead be found guilty of manslaughter and assault, because he was likely intoxicated at the time of the attack.

Starrett has admitted to the killing of his son, but has pleaded not guilty. Whether he was aware of his actions is at the crux of the trial.

Defence lawyer Rory Ziv argued Friday that his client is not criminally responsible because he was in a sleeping, automaton-like state during the attack.

He previously called up testimony from a sleep disorder expert, who concluded Starrett was likely experiencing parasomnia, a sleep disorder that involves undesirable occurrences during sleep.

Court has also heard from Starrett himself, who testified he has suffered from sleep problems for most of his life.

At the time of the offence, he was stressed about his finances and relationship with his partner. Starrett was also going through heroin withdrawal, had ingested a large number of Percocets and had debilitating back pain.

Starrett is in need of proper care and treatment and should be overseen by the Alberta Review Board, Ziv said.

"To say that this is a sad case does not capture the tragedy of this case," he said.

"There's never going to be an absolution."

Crown argument

Christensen-Moore, the Crown prosecutor, said in her closing argument that there was only one instance prior to the attack of a parasomniac event. It was described by Starrett, but never mentioned to a physician or family.

Inconsistencies in Starrett's evidence "ought to significantly hamper" the foundation for his defence, she said.

"There doesn't seem to be a real motive for this crime. However, following the commission of an offence, there can be a motive to reinvent how it happened."

Evidence before the court also demonstrated Starrett's anger issues, including testimony from a forensic psychologist, Christensen-Moore added.

The Crown holds Starrett acted in a fit of rage during the fatal attack but was aware of what he was doing.

However, the recent consumption of Percocets meant intoxication would affect his ability to form the intent required for a murder conviction, Christensen-Moore said.

She suggested he be found guilty of manslaughter and assault.

Justice John Henderson will deliver a verdict June 26.

Starrett is not in custody.