Marissa Shephard, 22, has been sentenced to 25 years with no parole for the brutal murder of her childhood friend

A 22-year-old mother has been sentenced to 25 years behind bars with no parole after the grisly murder of her childhood friend in December 2015.

Marissa Shephard was found guilty by jury last month of first-degree murder and arson with disregard for human life for her part in the murder of her 18-year-old childhood friend, Baylee Wylie.

The court was told Wylie had been found battered, bruised and dead, beneath a mattress by firefighters inside Shephard's burning home in Canada on December 17, CBC reported.

He had been stabbed and suffered more than 140 'sharp force injuries', most while he was alive. The jury heard he had been stabbed with multiple objects, including a broken mirror, a box cutter, a curtain rod, screwdrivers and a dagger.

Wylie had been tied to a chair and his face had been covered in plastic wrap, before a mattress was put on top of him and set alight.

Shephard (pictured) and two others covered Baylee Wylie's face with plastic wrap, stabbed him more than 140 times and covered his body with a mattress, which they set alight

Wylie was only 18 when he died in such a horrific manner. The court heard he and Shephard were childhood friends, who reconnected just a few months before his murder because he was working as a prostitute, and so was she

Following her the brutal murder, Shephard went on the run, Huffington Post reported. Police said the now 22-year-old was considered dangerous to the public because of the violent acts she had committed.

Shephard and her two co-accused, Devin Morningstar, 20, and Tyler Noel, 20, had been with Wylie at the young mother's home for what the jury was told was a drug-fueled night.

Shephard's defence lawyer, Gilles Lemieux, told the court it was a substance abusing lifestyle that had led to the death of Wylie, and begged the court to give his client a chance to raise her son.

'Four kids, four lives ruined,' he said.

'And the elephant in the room — drugs, alcohol and prostitution. It has caused immeasurable losses.'

Shephard told the court she had first tried crack at the age of 12, fell pregnant in Grade 9, and became a prostitute at 17

Her lawyer, Gilles Lemieux, said it was drugs, alcohol and prostitution that resulted in Wylie's murder

Shephard had earlier told the court she had become pregnant in Grade Nine, first smoked crack at 12 years old, and had become a prostitute at the age of 17, working under the name Emily.

This was her connection to Wylie, who were friends as children, but had reconnected over their job. Wylie also worked as a prostitute, she said.

Lemieux's plea to allow Shephard to be a mother saw Wylie's mother, Amanda, run from the court room in tears. The 18-year-old had been her only child.

Morningstar and Noel were both sentenced earlier this year, and Shephard was the final person to face trial, Global News reported.

In handing down her sentence, Justice Zoel Dionne said: 'Mr. Baylee Wylie was quite simply tortured to death'.

Shephard was given three years behind bars for the arson minus time already served, to be served at the same time as her first-degree murder sentence.

Noel was given life in prison with no parole eligibility for 16 years after pleading guilty to second degree murder.

Morningstar is serving a life sentence with no chance of parole for 25 years. He was convicted of murder and arson.