A Winnipeg woman who stabbed and killed her elderly neighbour in a random attack is appealing her 12-year prison sentence, arguing the law wasn't applied properly to her case and the overall punishment she got was unfit.

Melissa Gabriel, 37, will argue to Manitoba's Court of Appeal that she believes the sentence she received for killing Dorothy Dykens was "unreasonable."

Police found Dykens dead in her Tremblay Street home on May 17, 2015. The 89-year-old lived alone.

An autopsy revealed she was stabbed 68 times. Gabriel was renting a room from Dykens' neighbour who was on vacation at the time of the attack. The neighbour's dog was also found stabbed.

It was Gabriel who called 911 after the killing. Police found her on the floor of her living room surrounded by liquor containers.

She was not taking her medications as required and was at the time barred from drinking due to a probation order.

Gabriel had 55 prior convictions, 11 of them for violent crimes, court heard. She lives with several mental health conditions including post-traumatic stress disorder and doctors have diagnosed her as having alcohol-induced psychosis.

In sentencing her on June 23, Judge Ryan Rolston noted Gabriel was a "ticking time bomb" given her propensity for violence when she drank and that the combination of her mental illness and drinking had long been a problem for her — one she should have been aware of.

"She'd bury her head in the sand" when it came to dealing with her issues, Rolston said. "She has allowed herself to remain unchecked."

Gabriel requested a sentence of seven years.

Her argument for that hinged in large part on Rolston finding her mental illness should diminish her blame due to being sick when she committed the killing, and therefore not able to fully appreciate her actions.

Defence lawyer Matt Gould said Thursday he'll argue to the appeals court the judge was mistaken in finding Gabriel should get a stiffer sentence because she failed to manage her condition.

"She's mentally ill to start … she made a terrible error," said Gould. "The response to that error is extraordinarily harsh," he said.

A date to hear the appeal has not yet been set. Gabriel remains in custody.