Edmonton RCMP closed the case five years later, after a medical examiner determined her death was not criminal in nature, according to her mother, who strongly rejects that conclusion. "My daughter wouldn't just go and lay down in some farmer's field and die like that. That's stupid" she said, adding that she believes her daughter met with foul play.
An RCMP task force that is looking into the disappearances or deaths of almost 80 people, many of them women in the sex trade, is helping with the investigation, Corporal Wayne Oakes said.
A cause of death for Ms. Benwell has not been released, although the case is being treated as a homicide.
When the bar closed at 2:30 a.m., Barbara returned to the vehicle where she and her boyfriend continued fighting. The altercation escalated and the couple split. Her boyfriend stormed off in his car, leaving Barbara behind in the parking lot. Witnesses stated that her boyfriend drove off at 2:30 AM leaving Barbara alone where she reportedly was planning to hitch hike to a different party but she never got here.
The following morning, a man walking his dog discovered Barbara's fully-clothed, strangled body beside a gravel road near 80th Avenue and 6th Street N.E. in Calgary.
Although she was fully clothed circumstances led detectives to believe that she was sexually assaulted. A thorough examination of the crime scene also led investigators to surmise that she'd been killed at another location then moved to the gravel road some time later. Whoever gave Barbara a ride that night is in all probability, the same person who murdered her.
After further speculation the police believed that her murder was connected to Melissa Rehorek's who had been murdered the previous year on September 16th. She had last been seen leaving the YMCA where she was planning to hitchhike to the city for the weekend.
Police traced her movements the night before to the Highlander Hotel tavern, where she and her boyfriend had argued after closing time.
The daughter of a retired physician, MacLean was originally from Nova Scotia and had moved to Calgary, where she worked at the Royal Bank, the Calgary Herald newspaper reported after the murder.
The only suspect was Gary McAstocker who was a known sex offender. He committed suicide after he found out that the police wanted to talk to him about the murder of another girl named Tina McPhee.
McAstocker had just been released from prison after serving his full 11-year sentence for a 1982 rape and a subsequent 1988 sexual assault committed while on parole.
RCMP investigators also suspected her killer might be the same man who killed Melissa Ann Rehorek, 20, who was found Sept. 16, 1976, in a ditch along a gravel road about 20 kilometres west of Calgary near the Trans-Canada Highway. She had been strangled.
McAstocker was also reportedly the prime suspect in the 1976 murder of an Edmonton teenager, Marie Judy Goudreau, 17, who disappeared Aug. 2, 1976 on the way home to her family's farm on the edge of Edmonton. Her body was found two days later near Devon, southwest of Edmonton.
McAstocker hanged himself in 1994 in his Edmonton home hours before he was to be questioned by police.