MEDICINE HAT, Alta. - Hours after her family was stabbed and slashed to death, the 13-year-old girl accused of killing them casually talked about the sounds her little brother made as he died, court was told Wednesday.

James Whalley told the girl's first-degree murder trial she told him her little brother "gargled'' and that her boyfriend, 24-year-old Jeremy Steinke, calmly confessed to the killings.

The dramatic testimony in the third week of the young teenager's trial was the first time the jury heard evidence that she was near her eight-year-old brother when he died in his bedroom from a slashed throat.

Earlier in the trial, a medical examiner had testified that the deep cut had severed the child's jugular vein and larynx. Dr. Craig Litwin also told court that if a person's voice box was cut, there could be "some gurgling sounds.''

Whalley told the jury Wednesday that the quick discussion came up when his close friend Steinke and the accused pulled him aside and admitted that they had killed her family the night before.

"Jeremy said he'd gutted them like fish,'' Whalley said.

The accused's parents were found in the blood-soaked basement of their home, both dying from massive blood loss due to multiple stab and slash wounds.

Whalley, who ran into the couple as he was picking up a few belongings from his former residence, said he told them they were crazy and left the house.

"Who's going to believe that their best friend did something like that?'' Whalley asked the jury.

He told Crown attorney Stephanie Cleary that when the couple spoke to him, their tone was "completely mellow -- an everyday conversation like you and I are talking now.''

That evening, Whalley said he saw news of the killings on television and went down to the police station.

"I was frantic,'' he recalled. "I was freaking out. I didn't know what to think. I had a warrant out for my arrest.''

Under cross-examination from defence lawyer Tim Foster, Whalley maintained that Steinke's actual words were: "We killed my girlfriend's parents.''

The accused, who was 12 at the time of the deaths, can't be identified under provisions of the Youth Criminal Justice Act.

Steinke, who also faces the same three first-degree murder charges, has yet to enter a plea. And his trial date has not yet been set.

Outside of court, Foster said he wasn't expecting Whalley to say what he did. And now it's up to the jury to decide whether they believe him.

"Sometimes what we expect people to say, they don't say. And sometimes they miss things and leave things out and sometimes they add additional things,'' said Foster.

"It was a very eventful day in that sense as the evidence wasn't quite what any of us anticipated.''

Also on Wednesday, the jury heard more testimony that the accused and Steinke had lunch and relaxed at Whalley's old house just a few minutes drive from where her family's bodies were being discovered.

Another witness said the couple were sitting on a couch together, kissing, giggling and whispering in each other's ears.

"She seemed really happy,'' said 18-year-old Belinda Hope.

The trial has heard from the accused's friends and teachers, who said she underwent a marked transformation around the time she started seeing Steinke.

And she made it known she hated her parents for grounding her and trying to discipline her for dating a man nearly twice her age.

This week, the Crown has called a procession of witnesses who recall seeing the accused and Steinke both before and after the killings at drinking parties and other gatherings.

One witness even claimed to have snorted several lines of cocaine with Steinke in the hours before the alleged crime.