The two boys who have admitted to the brutal murder of Kimberly Proctor were avid players in an online role-playing game and experts say it's likely the line between fantasy and reality became blurred.

On Wednesday, a B.C. court heard how two teens, aged 16 and 18, planned the murder of the Colwood, B.C., girl online. They came up with code words to initiate the attack, maps of where to dispose her body and what kind of fuel to buy to burn her body.

They were also fans of World of Warcraft, a sometimes violent online fantasy game with 12 million subscribers around the world. Experts believe it perpetuated the violence against the 18-year-old girl and provided key information to police.

Bonnie Leadbeater, a psychology professor at the University of Victoria, says some kids have trouble knowing that what's acceptable in a game may not be in real life.

"You don't know which aggressive kid is going to take the fantasies of video games and try them out in reality. You just can't predict those very rare occurrences," she said.

"There would have been signs early. I don't know these two boys at all, but generally, kids who go on to kill other kids or to act out in this sort of extreme manner are having problems early.

After Proctor's murder, the boys told a friend on World of Warcraft what they had done. One of the teens admitted that the murder didn't feel like he thought it would.

Those messages were collected by police and used by prosecutors.

Now the teenage killers are undergoing psychiatric exams, and a judge will decide in March if they should be sentenced as adults.

With a report from CTV British Columbia's Lisa Rossington