With the verdict of first-degree murder in, the teen convicted in the killing of Stefanie Rengel now faces a battle over whether the court will sentence her as an adult.

"The Crown moves for an adult sentence, your honour," prosecutor Robin Flumerfelt told Justice Ian Nordheimer on Friday after the three-woman, nine-man jury had left.

The court will reconvene on Tuesday to start that aspect of the case.

The stakes are high for 17-year-old convicted murderer M.T., who can't be fully named under the provisions of the Youth Criminal Justice Act.

If she is sentenced as an adult, M.T. would get life in prison and be barred from seeking parole for at least five years.

Adults face an automatic sentence of life in prison with no parole eligibility for 25 years. However, M.T. was 15 at the time of the offence -- New Year's Day 2008.

If Nordheimer decides M.T. is to be sentenced as a youth, she would face a sentence of no more than 10 years, with six of those to be served in custody and the remaining four in the community.

Her identity would remain officially hidden from the public.

CTV legal analyst Steven Skurka said Saturday that Nordheimer would look at M.T.'s age, maturity and character when considering what to do. He would also consider the offence's seriousness and circumstances.

Two Mississauaga sisters convicted of first-degree murder in 2005 for killing their mother received the maximum 10-year sentences.

In 2007, a Medicine Hat, Alta. girl was found guilty of first-degree murder in the deaths of her parents and little brother even though they found her boyfriend Jeremy Steinke did the actual killing. She also received the maximum 10-year sentence.

She has been undergoing a program of intensive psychological treatment.

Steinke, an adult when he killed the three, received the automatic first-degree murder sentence for full adults upon conviction in December 2008.

The murders in that case occurred in April 2006 when the girl was only 12. The girl pressured Steinke, almost a decade older than her, to kill her parents because they disapproved of her relationship. They decided to also kill her brother, who was only eight, because they feared he could identify them.

The two had exchanged online love letters. The girl had written the following to Steinke: "I hate them (her parents). I have this plan. It starts with me killing them and ends with me living with you."

The Crown alleged that the girl counselled Steinke to kill her family rather than take part herself, although Steinke claimed at his own trial that she slit her own brother's throat.

M.T. isn't alleged to have killed Rengel, someone she had never actually met. Instead, she was shown to have pressured her boyfriend D.B., now 19, to kill the victim.

On Jan. 1, 2008, D.B. is alleged to have stabbed Rengel six times very close to her East York home. He will face trial on a charge of first-degree murder in the fall.

For months before that, the jury heard evidence that the two had intensively discussed killing Rengel. The Crown submitted huge volumes of evidence relating to the electronic communications -- instant messages, cellphone records -- of M.T. and D.B.

M.T. had essentially told D.B. that he wouldn't have any sexual relations with her until Rengel was dead. On the day of the murder, she had taunted him about being interested in another boy.

She reportedly bragged in a Facebook exchange with a friend that she made love with D.B. after Rengel's death.

Police videotaped an interview with M.T. about 12 hours after Rengel died.

Det.-Sgt. Steve Ryan conducted that interview, which many saw as chilling because of the blase nature of M.T., and he called this case a first for him.

"The age and the planning -- a 15-year-old girl planning a murder. It's rare," he told reporters on Friday after the verdict.

His opinion is that the crime committed warrants an adult sentence.

M.T. had been very expressionless throughout the trial, but cried after the conviction was registered. However, in the interview, the only time she cried is when she talked about the problems that Rengel had allegedly caused in her relationship with D.B.

Ryan said M.T.'s outburst in the courtroom was the only sign of remorse he's ever seen from her -- if indeed it was remorse.

While some of Rengel's friends rejoiced in M.T.'s conviction, another saw it as bittersweet.

"It's not something we can celebrate as a victory. It's a tragedy all around," said the Rev. Scott Patton of Presteign-Woodbine United Church.

He said Stefanie will be missed: "She was somebody that everybody just liked being around."

With a report from CTV Toronto's James MacDonald