One of Brett Wiese's killers has had her sentence reduced by the Alberta Court of Appeal and will spend just four years behind bars.

JFR, whose identity is protected by a publication ban, stabbed the 20-year-old University of Calgary business student to death at a house party in January 2013 because she was angry she'd been kicked out earlier.

The now 21-year-old was found guilty of second-degree murder last year and was originally handed an adult sentence for her crime — life in prison with no chance of parole for seven years.

The Court of Appeal imposed a youth sentence on Wednesday of four years in custody and three years of community supervision. She has already served a year and a half and will be released in 2019.

"The maximum youth sentence without credit for pre-sentence custody is sufficient to hold the appellant accountable for her offending behaviour," wrote Justice Ronald Berger in his decision.

A panel of three judges heard the appeal. The majority opinion concluded JFR's sentence should be reduced with Justice Brian O'Ferrell dissenting, saying he would have upheld the original sentence.

The young woman was 17 years old when she was kicked out of the Brentwood house party. Court heard evidence she was angry and left screaming, swearing and swinging punches at party-goers as she threatened to come back.

Around 3 a.m., the teen returned with about 10 friends. She confronted Wiese who she believed was responsible for kicking her out and stabbed him in the back.

"[JFR]... has taken steps to change her life and is genuinely remorseful for her conduct," wrote Justice Patricia Rowbotham in her written opinion.

Mitchell Harkes also stabbed Wiese several times as revenge for his friend JFR and her twin sister being kicked out of the party. He was handed a life sentence with no parole for at least 12 years.

Harkes has also filed an appeal.