The 24-year-old, known for his role as Jeffery Augustine on the teen series Riverdale, was sentenced Wednesday in British Columbia Supreme Court in Vancouver.
Prosecutors said he also planned to assassinate Canadian Prime Minister Justin Trudeau.
Ryan Grantham has confessed to shooting his mother in the back of the head while she was playing the piano at their home outside Vancouver.
“I Killed My Mother”
In a video taken after the murder, the Canadian actor filmed his mother’s body, saying: “I shot her in the back of the head. She would know it was me.’
After shooting his mother, he drank beer and smoked marijuana for several hours. He then packed his three guns with ammunition, twelve Molotov cocktails, camping equipment and set off on his way to Prime Minister Trudeau’s residence with navigation.
He drove about 200 kilometers east when he turned around and headed for the Vancouver police station. He bluntly told one of the officers upon arrival: “I killed my mother.”
The court also heard that on his way to see the prime minister, Grantham considered committing a mass act of violence on Vancouver’s Lions Gate Bridge or at Simon Fraser University, where he studied.
Former child actor Grantham appeared in one episode of Riverdale in 2019 and also starred in the popular series Supernatural and the 2010 film Diary of a Wimpy Kid.
The BBC reports that Grantham has been in custody for the past two and a half years. He has been in a program for the mentally ill since his arrest.
During his trial, his lawyers argued that he struggled with anxiety and clinical depression, and that in the months leading up to his mother’s murder, he had shown a desire to kill himself and hurt others.
He will not be eligible for parole during the first 14 years of his life sentence.