When Robert Pickton's lawyers argued for a new trial at Canada's highest court Thursday, they had some surprising allies -- the family members of some of his victims.

At issue in the Supreme Court of Canada was whether a mistake by the trial judge in answering a question from the jury unfairly influenced the verdict. The jury had asked if they could find Pickton guilty even if they didn't believe he acted alone.

"The question was not answered correctly. It was wrong in a number of respects," defence lawyer Gil McKinnon argued in court.

If the conviction were overturned, Pickton would be ordered to stand trial a second time. Crown counsel has already indicated that any new trial would cover 26 charges of murder against him, not just the six that he has already faced.

Without a new trial, those charges will never be heard.

Rick Frey's daughter Marnie disappeared in 1997. After a decade-long fight for justice and a marathon trial, Pickton was convicted of her murder and the killings of five other woman.

Despite the emotional anguish that would no doubt accompany an overturned conviction, Frey told CTV News he would welcome a new trial.

"There's a lot of unanswered questions," he said. "I know it costs a lot of money, but I mean, you still have to have justice.

The court has reserved judgment on the matter, and is expected to make its decision in a few months.

With a report from CTV British Columbia's Stephen Smart