Video played in court Wednesday showed a room with bunk beds where seven of the weapons were found, including a loaded sniper rifle, along with a letter from a chief firearms officer addressed to Sawyer Robison.
On the floor nearby was a binder labelled "Special Forces Sniper Training and Employment (Headquarters, U.S. Army)."
Robison, 30, stood in court on the first day of his trial and pleaded not guilty to the counts against him, which also include assault causing bodily harm and four weapons-related charges.
Robison, described by residents as a quiet photographer and musician, was arrested following a standoff on his family's farm near Killam, southeast of Edmonton, in 2012.
At the time, RCMP said that a domestic violence assault led four officers to search for an illegal handgun on the property. Two Mounties walked into a house and shots were fired.
Constables Sheldon Shah and Sidney Gaudette were hit but managed to get out of the home and were taken to hospital.
Following a lengthy standoff, Robison's uncle, Bradford Clarke, was found dead in the house. Officers began a search for Robison, who they alleged had been in the home at the time of the shooting and fled in a black pickup truck.
He was arrested three days later after his parents appeared before TV cameras and pleaded for him to turn himself in.
Robison was also accused of second-degree murder in the death of his uncle, but that charge was discontinued during a preliminary hearing.
Cpl. Christine Bramhoff, a forensics officer who examined the scene, showed the judge photos of a naked man in a pool of blood on the kitchen floor. He had a head wound and two handguns were next to his body, one almost under his left hand. Court also heard a bathtub in the home was full of water and police believe Clarke had been having a bath before the shooting.
Bramhoff listed off more than two dozen spent bullets, fragments and cartridges found in several rooms of the cluttered bungalow. Two bullet holes were discovered in a large living room window.
There were also what appeared to be several ammunition re-loading stations throughout the home, she said, including one in the basement where officers found more guns in a closet and a bullet-proof vest hanging on a wall.
Bramhoff next examined a truck on a nearby grid road where Robison was arrested. A sleeping bag and ski mask were in the box of the truck. Bottled vitamin water, dried fruit and a knife were in the back seat.
She said it's believed Robison hid out in an office trailer at a nearby oil lease site, where officers found empty soda and juice bottles and a box of oatmeal cookies.
A black truck registered to Robison's father was later found hidden among other vehicles and farm machinery on an area property, said Bramhoff. A sniper rifle with its serial number filed off, boxes of cartridges and another bullet-proof vest were inside.
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