WINNIPEG — The mother of a Winnipeg girl killed 30 years ago says she is “terribly surprised” by a Supreme Court decision that has ordered a new trial for the man convicted of her daughter’s murder.

Wilma Derksen says she still believes Mark Grant abducted and killed 13-year-old Candace in 1984.

But she says she respects the process and if there is doubt about his guilt it should be dealt with in the courts.

“We believe that the process is good and it is needed and if there is doubt out there then lets talk about it or drop it — whatever has to happen,” she said Thursday, sitting in the living room of the family home.

“I have to admit, though, that I am convinced.”

Grant’s lawyer Saul Simmonds said he expects to apply for bail for his client and he hopes the Crown will decide not to go ahead with a second trial.

Grant was found guilty of second-degree murder in 2011.

The conviction, which carried a life sentence with no chance of parole for 25 years, was overturned by the Manitoba Court of Appeal in 2013.

Grant’s lawyer had argued that the trial judge was wrong to deny him the right to present evidence that could show Derksen might have been killed by someone else.

A new trial was ordered but provincial prosecutors appealed to the high court after being granted leave to do so in 2014.

In a unanimous 7-0 decision released Thursday, the Supreme Court upheld the Appeal Court’s decision.

“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.

“I agree with the Court of Appeal that a new trial is required.”

Candace disappeared on her way home from school and her body was found six weeks later, bound and frozen, in a storage shed near her home.

Grant — who repeatedly denied guilt — wasn’t charged until 2007 after numerous tests on a piece of twine used to bind the girl.

In the Court of Appeal ruling, Justice Michel Monnin wrote that some evidence not presented at trial “could provide the basis upon which a reasonable, properly instructed jury could acquit.”

Now prosecutors will need to decide whether to hold another trial or drop the case.