The Manitoba Court of Appeal on Wednesday ordered a new trial for Mark Grant in the 1984 death of 13-year-old Candace Derksen.
The Appeal Court said the original judge didn't consider some evidence that could cast doubt on Grant's guilt.
Wilma Derksen, the girl's mother, says she hopes the Crown will seek to challenge the new trial before the Supreme Court.
Manitoba Justice says it hasn't decided yet whether it will file such an appeal, go ahead with a new trial or drop the case.
The Appeal Court ruling means Grant can apply for bail.