TORONTO - A Superior Court judge on Tuesday ordered a mental health evaluation of the teenage girl found guilty of first-degree murder in the stabbing death of Stefanie Rengel.

During the first day of the sentencing process, Justice Ian Nordheimer agreed with the Crown's request for the review, a move supported by the teen's defence lawyer.

"I do believe a psychiatric assessment would be helpful," Nordheimer said.

Rengel, 14, was stabbed six times outside her home on New Year's Day 2008 and left to die in a snowbank.

The 17-year-old girl, who can only be identified as M.T., was found guilty last Friday of counselling her then-boyfriend to kill her perceived rival.

He faces a murder trial later this year.

Nordheimer must ultimately consider whether the convicted girl will be sentenced as an adult.

The judge also ruled Tuesday that the defence can arrange its own psychiatric or psychological assessment of the girl.

Her lawyer Marshall Sack disagreed with the choice of psychiatrist proposed by the Crown, saying the doctor took three months to visit a youth offender in another one of his cases.

"I agree absolutely there has to be a psychiatric assessment," Sack said. "The real question I have: how do we determine the identity of the psychiatrist?"

Crown prosecutor Robin Flumerfelt objected, saying: "I don't think it's appropriate to engage in some sort of psychiatrist shopping."

Ultimately, the judge agreed to accept two assessments.

The girl is scheduled to appear in court April 21.

The Crown is seeking an adult sentence, and if the judge agrees, M.T. could be sentenced to life in prison without the possibility of parole for five to seven years.

If sentenced as a youth offender, the maximum penalty is 10 years, which includes four years served in the community.

The Crown successfully argued that thousands of emails, text messages and online chats presented to the jury at trial amounted to a murder plan.