CALGARY - Several jurors in the trial of an Alberta man accused of killing his 12-year-old girlfriend's parents and younger brother wiped away tears Wednesday as they viewed graphic photographs of the murder scene.

Others shook their heads as they paged through the images as part of Jeremy Steinke's first-degree murder trial.

The pictures show the eight-year-old boy lying on his side in bed, wearing only a small pair of dark blue underwear. His legs are splayed, his mouth and eyes open.

His small body and several stuffed animals and toys beside him are coated in blood.

"You can see a little plastic light sabre and his pair of pants ... with blood on them and also on the carpet," said Sgt. Gerald Sadlemyer, a forensic expert with the Medicine Hat police.

Several jurors grabbed tissues as they saw pictures of the dead boy. Another forensic expert also struggled with describing the evidence from around his room, choking up briefly.

On Tuesday, the jury heard Steinke, 25, admit to killing the girl's parents in a taped conversation he had with an undercover police officer. Steinke said he watched as the girl killed her younger brother by slitting his throat.

The couple's daughter, now 15, has already been convicted of three counts of first-degree murder and is serving a 10-year sentence as part of a rarely used intensive rehabilitation program.

Steinke told the officer it was the girl's plan to kill her family and he went along with it out of love. The girl's parents disapproved of her relationship with him because he was a decade older, and had tried to forbid the pair from communicating.

He said that the girl's father tried to stop him after he stabbed her mother in the basement.

The man rushed at him and pushed his thumbs into Steinke's eyes before trying to stab him with a screwdriver, Steinke said on the recording.

"I was surprised I came out on top. I thought I was dead man."

Photographs of the area where the confrontation took place show the father on his back on the floor, a dark pool of blood below his head soaked into the carpet. He's wearing nothing but shorts and a watch. His hands are raised in loose fists.

Signs of a struggle are evident, with couch cushions lying on the floor next to exercise equipment.

A small screwdriver and a knife with an approximately 16-centimetre blade, bent at the tip, were nearby. Another officer referred to the knife as a "filleting-type knife."

"There's blood all over the place," Sadlemyer said, describing the scene for the jury.

Pictures of the girl's room show bright, hot-pink walls with a taped pentagram along one wall. A pair of pyjama pants with blood on them were seized from the room.

Forensic experts also examined a truck driven by Steinke, the trailer where he lived, and the truck where the pair were discovered the day after the killings.

Michael Storozuk, a former Medicine Hat police officer, said he lifted several footprint traces and fingerprints from around the house and yard.

He said the footprints were from the same type of shoe that was seized from the truck where Steinke was found.

No fingerprints matching Steinke's were found in or around the house, Storozuk testified.

Jurors are expected to hear testimony about online communication between the pair Thursday.