One of the two men convicted of murdering 14-year-old runaway Chelsea Acorn is being given a new trial because the judge who heard his case failed to give proper instructions to the jury.

Dustin Blue Moir was found guilty of first-degree murder in 2010, four years after Acorn’s strangled, bludgeoned body was discovered in a shallow grave outside Hope.

But the B.C. Court of Appeal set that conviction aside Wednesday after ruling B.C. Supreme Court Justice William Grist had erred by allowing inconsistent statements into evidence.

“There were two version of the events available to the jury in this case, one in which [Moir] was an active principal or aider of the offence of murder; the other in which he was a fearful bystander and accessory after-the-fact,” Justice Elizabeth Bennett wrote in her decision on behalf of the three-judge appeals court panel.

“The trial judge did not instruct the jury on the proper use of prior consistent and inconsistent statements from witnesses. By failing to do so, he fell into error. This error alone requires a new trial.”

One such statement came from Josh Gordon, the man who lent the shovel used to dig Acorn’s grave.

Gordon told police he gave the shovel to Moir, then testified he’d actually handed it to the co-accused in the case: Moir’s drug dealer father Jesse Blue West.

Asked about the divergent claims, Gordon testified: “I really don’t recall who I gave the shovel to. Jesse West did ask for it though.”

Justice Bennett said the inconsistency should have made the claim inadmissible.

“Generally, a prior inconsistent statement of a non-accused witness is only admissible to challenge the credibility of that witness. If the witness adopts the prior statement, then the statement may be used for the truth of its contents,” she wrote.

“The exception to this rule, based on necessity and reliability, is not present here. This is a complicated rule of evidence.”

During the police investigation into Acorn’s death, Moir told an undercover officer his father had offered to pay him $15,000 to help kill and bury the teen.

He said they drove Acorn to a campsite by the Coquihalla Highway in June 2005, bound her with duct tape and choked her to death before carrying the body to an open grave and throwing rocks on top of her, the court heard.

But at trial, the accused claimed he only helped bury the teenager, and denied knowing his father’s plan to kill her when he agreed to go camping.

Justice Bennett said Grist correctly told the jury to be cautious while considering statements made to an undercover officer.

“The law has had experience with false confessions of crime by those who were later exonerated. People will at times confess to crimes they have not committed,” Grist said.

Moir testified that he felt pressured to exaggerate his involvement in the murder to stay in his father’s criminal organization.

A number of witnesses, including some called by Crown, also supported the claim that Moir and his friends feared his criminal father. The court heard that Moir, who was 19 at the time of the murder, had been in a relationship with Acorn, and that both he and West had slept with her on their way to the campsite.

West was found guilty of first-degree murder last week. He has yet to be sentenced.

The date for Moir’s new trial has not been set.