The two teens responsible for the brutal murder of 18-year-old Kimberly Proctor have both been diagnosed as sexually sadistic psychopaths, a B.C. court heard Tuesday.

The two boys, who were 16 and 18 at the time of the murder, pleaded guilty last year to killing Proctor and burning her body before dumping it on a trail near Colwood. The pair was charged with first-degree murder, forcible confinement, sexual assault and indignity to human remains in her death.

Psychological and psychiatric reports presented by Crown prosecutors Tuesday described the younger boy as sexually attracted to the psychological and physical suffering of others. The doctors who reviewed him said he is at high risk to reoffend and should be jailed for a long time to ensure public safety.

They said he showed no remorse for the murder.

The boy was described as bright and curious -- even brilliant -- by the doctors. But he had a troubled home life, and entered counselling for violent behaviour at the age of six.

At 11, he started setting fires, and when he was 12, he began hitting his mother and would later be charged with assault for an attack.

That aggressive behaviour escalated over time. He got into fights with other boys, and on one occasion, used chains to hit a victim in the head. The other boy needed staples to close the wound.

The boy's father is behind bars for the brutal murder of a teen girl under very similar circumstances. In that case, too, the girl was lured, beaten, bound, sexually assaulted, choked and killed.

Because the son is a young offender, neither he nor his father can be named.

Second boy has violent past, too

The two teens met in grade five, and had a history of skipping school together and lighting fires. They were involved in joint rape fantasies for at least a year before Proctor's murder.

The older boy became infatuated with knives and got into drugs and alcohol at 14. The doctors said he like to burn things and got into trouble at school.

In 2003, when he was just 11, a psychiatric assessment revealed a trend of escalating violence against his mother and sister. He was arrested three years later for threatening his mother with a knife.

His mother reported that he once kicked the family dog, breaking bones.

The doctors who examined the older boy diagnosed him as a pathological liar with narcissistic traits, and suggested he should be monitored for the rest of his life. He also showed little remorse for his actions.

Defence lawyers did not question the experts' reports.

Crown seeks adult sentence

Prosecutors are arguing that both of the killers should be sentenced as adults in Proctor's murder.

A youth sentence for the teens would mean a minimum jail term of 10 years without parole. That jumps to life with 25 years without parole if they are sentenced as adults.

The details of Proctor's murder were so repulsive and appalling, some officers who worked the case have gone into counselling.

On March 18, 2010, after declining the boys' advances, Proctor was lured to a home of one of the boys where her hands and ankles were duct-taped. They stuffed a sock in her mouth and sexually assaulted her for hours.

A knife was used to mutilate her body and she eventually died. An autopsy revealed she couldn't breathe because of the tape over her mouth.

Her body was placed in a freezer in the garage. The next day the teens carried her body in a duffel bag on a public bus to the Galloping Goose Trail, where they lit her on fire.