When "Buffy" was 16 years old, she helped to murder and sexually assault 13-year-old Nina Courtepatte.

In April 2005, Courtepatte was kidnapped and taken to a golf course west of Edmonton by three men and two women, one of them Buffy. The girl was raped and bludgeoned to death.

Buffy, whose identity remains protected under the Youth Criminal Justice Act, was the youngest of the five convicted killers.

In 2009, Buffy was sentenced to four years in custody, to be followed by another three years of supervised probation.

That sentence is officially over on Nov. 9, 2016.

Making her final required court appearance this week, Buffy spoke about some of the challenges she has faced, and expressed her thanks to those who have helped her along the way.

In his 2009 sentencing decision, Justice Adam Germain noted that in 2005, Buffy "was essentially living in the West Edmonton Mall … doing what she could to stay alive."

The teenager was using crystal meth and had adopted her nickname from the television show Buffy the Vampire Slayer. She sharpened her teeth, drank blood and wore a set of throwing knives.

The television series was the inspiration for the teenager's self-adopted nickname, Buffy. (Supplied )

That night on the golf course, Buffy put her foot on Courtepatte's stomach to hold her down as the girl was being raped. Then she used a throwing knife to slash the young teen's neck. As the judge noted, "This was occurring around the time others bludgeoned Ms.Courtepatte to death."

Germain convicted the teenager of second-degree murder and aggravated sexual assault, and gave her the harshest possible sentence allowed under the Youth Criminal Justice Act.

'Being an adult is never easy'

Buffy appeared before Germain one last time this week in an Edmonton courtroom.

She's 27 years old now, working full-time and engaged to be married.

Buffy wrote a two-page letter to the judge. It was made a court exhibit and a copy was obtained by CBC News.

"Since we started this years ago, I've run into quite a few snags and forks in the road," she wrote.

Youth advocate Mark Cherrington said the use of pepper spray is causing pain and suffering to children. (CBC)

"Being an adult is never easy. I can clearly see that all we can do is transition the best way we can because let's face it, jumping into things isn't always the greatest thing to do, even with the best intentions."

The young woman thanked all those who have helped her over the past decade, including her probation officer, the Elizabeth Fry Society and court youth worker Mark Cherrington.

'This is what the Youth Criminal Justice Act is for'

"I'm so happy for her. The outcome speaks for itself," Cherrington said in an interview with CBC News.

"This is what the Youth Criminal Justice Act is for — for working with people such as this girl and providing her the best protective factors we can, and making an effort that's not just an hour or a day or a week or a month, but years … a decade of continued help and rehabilitation and reintegration."

According to a letter submitted by Buffy's probation officer, there were setbacks along the way, with some breaches of the terms of her probation.

In her letter, Buffy thanked the judge "for giving me more than a few chances." She added, "I'm pleased to inform you I have not had any breaches in the past year."

Germain told the court he thought Buffy's letter showed "amazing insight" and "a big improvement from where we were seven or eight years ago at the start of the case."

"I almost feel like we've become family," Germain said. "But I don't think you'll be offended when I say I'm glad we've come to the end of the road."

Then he turned toward the young woman in the prisoner's box and said, "All the best to you. This review is now concluded."

Buffy left the courtroom with her fiancé.

She was smiling.