WINNIPEG -- One of the last people to see 13-year-old Candace Derksen alive testified Monday that he had a crush on the girl, jokingly threw snow in her face and briefly saw her walk away from her school.

It would be six weeks before her frozen, hog-tied body was found inside a plywood shed in an industrial yard, and two decades before a man with a long criminal record was charged with the killing.

"I said, 'Are you going home?' and she said 'Yeah,"' David Wiebe told court.

"I said, 'OK, if I had time I'd walk you home."'

Wiebe was the first witness to testify at the retrial of Mark Edward Grant. Grant was charged in 2007 following DNA testing on twine used to bind Derksen, and convicted in 2011 of second-degree murder.

The conviction was overturned two years later when an Appeal Court ruled the trial judge erred in not allowing Grant's defence to present evidence that pointed to another possible killer -- an unidentified person who tied up a 12-year-old girl in 1985 while Grant was in custody on another matter.

The Crown on Monday proceeded with a new trial which is scheduled to last 34 days.

Grant, now in his 50s and dressed in a dark suit, said "not guilty" as he was asked for a plea on a charge of second-degree murder. Not far behind him, the victim's parents, Cliff and Wilma Derksen, sat quietly.

Wiebe told the trial he stayed at school that day -- Nov. 30, 1984 -- for a driver's education course and choir practice. He was 15 and knew Candace from summer camp. He recalled Wilma Derksen tracking him down at the school a few hours after he saw Candace leave.

"After choir, Wilma Derksen walked toward me and asked if I had seen Candace."

A statement Wilma Derksen gave to police at the time was read into the record by the Crown. She told police she had talked with Candace after school by phone and told her to walk home.

The trial also heard from two workers at the industrial yard where Candace's body was found.

Owner Frank Alsip said he was alerted by one of his employees, went to the shed, saw Derksen's body and called police. That employee, Victor Frankowski, has since died. In a police statement in 1985, he told police he discovered the body.

"I thought it was a doll ... I looked again and thought it was too big for a doll," his statement read.

Grant did not know the Derksens, and the defence questioned witnesses about the possibility someone other than Grant may have killed Candace.

Under cross-examination, Wiebe admitted he did not watch Candace long enough to see which direction she walked after leaving the school.

"If she got into a vehicle, it would be unknown to you," defence lawyer Saul Simmonds said.

"Unknown to me. Correct," Wiebe replied.

Alsip said under cross-examination the yard had little in the way of security measures in 1984 -- no video surveillance, no fence and no night watchmen -- that would have prevented anyone from getting access to the shed.

Outside court, Candace's parents said a new trial after 32 years is not easy, but they were willing to let it unfold.

"It's something that we just have to be patient with," Cliff Derksen said.

"We feel we know the truth, and now we have to go through it again."