03/05/2015 04:00 EST | Updated 05/04/2015 05:59 EDT

Mother of slain Winnipeg girl 'terribly surprised' top court orders new trial

WINNIPEG - The mother of a Manitoba girl killed 30 years ago expressed surprise Thursday following a Supreme Court decision that ordered a new trial for the man she firmly believes killed her daughter.

"We are totally flummoxed, totally in shock," Wilma Derksen said as she sat in her living room beside her husband, Cliff.

Candace Derksen was 13 when she disappeared on her way home from school in Winnipeg in 1984. Her body was found six weeks later in a storage shed near her house. She had been tied up and left to freeze to death.

Mark Grant was convicted of second-degree murder in 2011, but the Manitoba Court of Appeal overturned the conviction in 2013 and ordered a new trial.

Provincial prosecutors appealed to the Supreme Court, which upheld the Appeal Court ruling in a 7-0 decision.

Wilma Derksen said she still believes Grant abducted and killed Candace.

"We believe that the (appeal) process is good and it's needed, and if there is doubt out there, then let's talk about it or drop it," she said.

"I have to admit, though, that I'm convinced (of Grant's guilt) ... I can't not be convinced."

The case against Grant hinged on DNA evidence from hair and fibre samples collected in the shed.

RCMP tested the twine used to bind Derksen in 2001, but results were inconclusive. A private lab, Molecular World in Thunder Bay, Ont., tested the twine and hair again in 2007. It was after that test that Grant was charged.

Grant, who is now in his 50s, has a long criminal history. He has spent nearly half his life behind bars for 23 offences. He has repeatedly denied killing Derksen.

When the Manitoba high court overturned his conviction, it said the trial judge erred in not allowing the defence to present evidence that pointed to another possible killer — an unidentified man who tied up a 12-year-old girl in 1985 while Grant was in custody.

The Supreme Court agreed.

"In this case, I conclude that the trial judge erred in evaluating and assessing the credibility of the unknown third-party suspect evidence on a balance of probabilities," Justice Andromache Karakatsanis wrote on behalf of the court.

Grant's lawyer said he plans to apply for bail.

"Our hope is that the Crown will re-evaluate their case and not proceed against Mr. Grant," Saul Simmonds said.

He also said the DNA evidence against Grant in the original trial was flawed.

Manitoba Justice Minister James Allum said in a written statement that his department will take time to review the ruling and "a decision will be made ... within the shortest time frame possible."

The Derksens have worked to help other families victimized by crime. They have tried to establish a support centre for victims in Winnipeg that would be called Candace House. They hit a roadblock last year when some people objected to the building they had in mind — a historical site that had been a museum.

Wilma Derksen has written a book about her daughter's death. The couple said Candace would want other children to be protected.

"Candace had our ideals ... and she had the basics that we had as far as a philosophy of life," Cliff Derksen said.

"Of our three children, Candace was the (most) sanguine. She was the one that inherited the love of people," his wife added.

"She would be very concerned about the safety of other children and would be anxious that there be justice, because that's the type of person she was."