SURREY, B.C. -- A young man who shattered a community's sense of safety with the murder of a 15-year-old girl needs to be supervised indefinitely because he cannot control his violent sexual behaviour, a youth forensic psychiatrist said at the man's sentencing hearing.

But Dr. Paul Janke, with B.C.'s youth forensics psychiatry service, said the man's explanation of the attack as an attempt gone wrong to overcome his anxiety and shyness around girls has "essentially no credibility."

"It's not uncommon for sexual offenders to talk about engaging in forceful sexual activity because they're not capable of acting otherwise," Janke told court during a hearing to determine whether the man, now almost 21 years old, should be sentenced as a youth or as an adult. The man cannot be named because he was 17 at the time of the attack that killed Laura Szendrei in September 2010.

"For the proposition that somehow that's going to relieve the person of that issue and allow them to function normal sexually, I've never heard of that."

Court has heard that five months before Szendrei was sexually assaulted then killed, the man also committed three sexually-motivated attacks against other women. The man has admitted to being aroused by bondage, domination and sadism.

Janke, who interviewed the man for four hours between January and February, testified he didn't believe the man when he denied planning to attack Szendrei and when he insisted that he now feels more comfortable around women.

Szendrei was attacked in the afternoon while she was walking through a park to meet friends. According to evidence presented in court, the man said he had wanted to subdue Szendrei by wrapping a plastic strap around her neck, and then rape her. But the girl screamed and got away, after which the man beat her over the head several times with a metal pipe he had brought with him.

The man was trying to get away when he went back to retrieve his items. By then, Szendrei's friends had arrived and found her severely wounded. The man told the group he had heard something, and volunteered to help look for Szendrei's attacker.

The man pleaded guilty to second-degree murder last year. He was originally charged with first-degree murder in 2011 when he was arrested. The arrest came after police conducted an undercover sting.

Janke said it is alarming that the man's violent sexual behaviour escalated within only a few months and that he appeared to show no emotion during the assessment about having killed someone.

"It is somewhat surprising that an individual of at least average intelligence, of relatively benign upbringing, who is well-socialized would not at least try to present some expressions of remorse," Janke told the court. "With (him), it was more a case of simply no expressions of grief other than concern for himself, and some concern for his family that was tempered by meeting his own needs as well."

Given the severity of his crime, his preference for coercive sexual behaviour, and the high tendency for people in the man's age group to reoffend, Janke said he believes the man needs intensive treatment, including access to a machine to test his level of sexual arousal. He would also need indefinite supervision. Neither are things that the youth justice system can provide, said Janke.

"In the absence of the ability to physiologically assess his arousal, given the nature of his actions, it would be my opinion that he would be far outside the range of the youth that we treat," he said. "To the best of my knowledge, we have not delivered treatment to a youth who has committed murder in the course of a  sexual acting-out, and I would not support our service providing treatment to an individual in that setting."

Janke's risk assessment appears to agree with that of the defence's forensic psychiatrist. Dr. Kulwant Riar also said earlier this week he believes the man poses a high risk to reoffend, and should be sentenced as an adult so he can receive the most effective treatment.

If sentenced as an adult, the man would receive life imprisonment with no ability to apply for parole. If he receives a youth sentence, he will receive seven years, with four years served behind bars and the remaining served in the community.