Melissa Todorovic, a convicted teen murderer, will be transferred to an adult prison despite pleas to allow her to stay in a youth facility.

Todorovic, 19, was in court on Thursday, asking to stay at a youth detention centre after she turns 20 next month.

She was convicted of first-degree murder for masterminding the killing of perceived rival, 14-year-old Stefanie Rengel, four years ago.

Rengel was stabbed six times and left to bleed to death in a snowbank on New Year's Day in 2008.

David Bagshaw, 18 at the time of the killing, was also convicted of first-degree murder and sentenced to life in prison.

Todorovic's lawyer, Brian Snell, told the court that it would be in his client's best interest to stay at the youth centre.

Stephanie Rengel, 14, was stabbed to death outside her home on Jan. 1, 2008. (Courtesy Toronto Police Service)

He filed court documents that say she is a straight-A student, is a role model in the facility and is working toward a biology degree.

He argued that Todorovic uses a laptop for her studies, but they are banned in federal prisons.

Snell said he was concerned an adult facility will stunt her rehabilitation.

But in announcing his decision Justice Ian Nordheimer said he believed Todorovic has not changed from the "manipulative" offender he sentenced to life.

Snell has filed an appeal of her 2009 conviction that if successful, will result in a new trial.

That appeal is expected to be in court early next year.

The Crown wanted her transferred to an adult facility to serve out her sentence, saying she has not taken steps toward rehabilitation and is still dangerous.