BARRIE, ONT. -- The trial of a man accused of killing a father and son in an Allandale neighbourhood in Barrie began this week with three police officers taking the witness stand to recount the gruesome discovery made on Feb. 8, 2017.

After receiving two 911 calls from inside a William Street apartment, police found the bodies of 51-year-old James Pasowisty and his 19-year-old son, Nick Pasowisty, with multiple stab wounds.

"It looked like it would be impossible to survive that," testified Const. David Edgar.

Const. Kevin Barkley stated the smell inside the second-floor apartment reminded him of a butcher shop, describing the stench as overpowering. Barkley recalled seeing blood in the snow on the front lawn.

Hours after the discovery, police arrested Dyrrin Daley, who they said appeared to know both victims at a nearby Marcus Street home.

Daley confessed to killing the men to police during his arrest, claiming self-defence, though it's unclear what sparked the violence.

A witness and friend of Nick's told the court James had at times sold him marijuana.

Daley, now 28, is charged with first-degree murder in Nick Pasowisty's death and second-degree murder in James Pasowisty's death.

The trial is expected to last several weeks.