They felt like jumping up and down and shouting, but Chelsey Acorn's family managed to limit themselves to a clap, tearful embraces and murmurs of "Yes!" when the teen's killer was found guilty of first-degree murder Monday.

"It was relief. It was pure - it almost makes you weak," said Acorn's cousin, Stacey Laybolt outside B.C. Supreme Court in Chilliwack. "You dream about it, you think about it, you feel it in your heart that that's what it's going to be, but until you actually hear it, you have that little bit of doubt that something will go the other way."

Jesse Blue West, 60, will serve a mandatory life sentence with no chance of parole for 25 years. A jury convicted West's son, Dustin Blue Moir, of first-degree murder in February 2010 and he got the same sentence.

Acorn was 14 years old when she ran away from her Abbotsford foster home in June 2005. It's believed she was murdered sometime between Oct. 1 and Dec. 31, 2005.

Hikers found her body in April 2006 along the Coquihalla River just north of Hope.

Acorn had been strangled and buried naked in a shallow grave, with her head crushed by a rock.

The Crown set out to prove at trial that both West and Moir planned and participated in Acorn's murder. The prosecution's case was largely based on incriminating statements West made during a "Mr. Big" undercover operation and after his arrest.

West, however, testified he lied to the undercover officers to appear tough and keep his job with the fictional criminal organization.

West said Moir killed Acorn by accident when he struck her during an argument. He then panicked and buried Acorn's body to cover up the crime and protect his son.

Justice William Grist called West's description of his involvement in Acorn's death "totally incredible."

"His account was incapable of belief or sustaining a reasonable doubt," Grist said.

The Justice noted West's description of where Acorn died and was buried wasn't accurate.

Grist said there was also a "striking inconsistency" between West's description of the blow allegedly inflicted by Moir and the evidence detailing the damage to the teen girl's skull.

West's testimony was "an ongoing invented narrative" that he made up as he went along, said Grist.

West, who came to court shackled and wearing a dress shirt, slacks and socks, did not visibly react to Grist's decision.

Defence lawyer Brian Coleman said, "I thought he took it very well." Coleman said West has not yet indicated whether he will appeal.

On behalf of the investigators who worked on the case, Integrated Homicide Team spokeswoman Sgt. Jennifer Pound said Monday's decision was a successful ending to the investigation.

Acorn's mom, Lisa, declined to speak with media outside court.

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