A former actor on the CW series "Riverdale" has been sentenced to life in prison after admitting to killing his mother and planning to assassinate Canadian Prime Minister Justice Trudeau. 

Ryan Grantham, 24, was sentenced at British Columbia Supreme Court in Vancouver on Tuesday. The actor is also ineligible for parole for the next 14 years.

Grantham had previously pled guilty to the second-degree murder of his 64-year-old mother Barbara Waite.

Waite was reportedly playing piano in the family's Squamish, British Columbia home on March 31, 2020, when her son shot her in the back of the head. 

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Canadian actor Ryan Grantham poses for cameras

Actor Ryan Grantham arrives at 2013 UBCP/ACTRA Awards on November 24, 2013, in Vancouver, Canada.   (Andrew Chin/Getty Images)

During a June hearing, prosecutors said that the young actor recorded a GoPro video in the wake of the killing and recorded his mother's dead body.

"I shot her in the back of the head," Grantham reportedly admitted on video. "In the moments after, she would have known it was me."

Grantham reportedly wanted to shield his mother from witnessing the acts of violence he planned to commit after, according to prosecutors. Her body was soon found by Grantham's sister, Lisa.

The day after the killing, the actor reportedly packed his truck up with Molotov cocktails, guns and ammunition and drove east with the intention of killing Trudeau in Ottawa. 

Grantham then turned around after thinking about committing a mass shooting at Simon Fraser University, where he was enrolled. He eventually turned himself in to the Vancouver Police Department that night.

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Justin Trudeau speaking

Grantham admitting to planning to assassinate Canadian Prime Minister Justin Trudeau before eventually turning himself in. (DAVE CHAN/AFP via Getty Images)

The young actor had reportedly experienced feelings of depression and self-hatred, which prosecutors believe was exacerbated by isolation, smoking an excessive amount of cannabis and watching gory videos on the Internet.

In a journal entry written the day of the killing, Grantham reportedly apologized to his family and said "no one" would understand him.

"I'm so sorry mom, I'm so sorry Lisa... I hate myself," he wrote, according to prosecutors. "There's a lot of media of me out there… film and TV… hundreds of hours of me that can be viewed and dissected... No one will understand."

Justice Kathleen Ker noted that Grantham was receiving counseling in prison and appeared to be improving, according to the CBC.

Still scene from Riverdale

Grantham appeared on the CW's hit series "Riverdale" as minor character Jeffery Augustine in Season 4. (Diyah Pera/The CW )

Ryan Grantham portrayed teenager Jeffery Augustine on the horror-crime series "Riverdale," which is inspired by the "Archie" comic book series. He appears in Season 4 for killing a main character, Fred Andrews, with his father's truck.

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His other credits include minor roles in the TV series "Supernatural" and the 2013 movie "Diary of a Wimpy Kid."