(NewsNation) — Mary Ann Hayes was found dead in her north suburban home in 1996. Authorities ruled her death a suicide. But a team of criminal justice experts is now pushing to reopen the case, claiming evidence shows she may have been killed.

Mary Ann’s son, Steven Altman, was also found dead the morning of May 11, 1984.

Experts push to reopen 1996 Chicago mom death investigation

“There was just nothing in this case at any point as we went along where we said, ‘Yeah, that does raise questions. Maybe it is a suicide,’” said Casey Gwinn, former San Diego city attorney and president of Alliance for Hope International.

Alliance, a nonprofit advocacy group, trains law enforcement and other professionals throughout the U.S. to identify and investigate strangulation deaths and staged crime scenes.

“We don’t believe it was ever treated as a crime,” Gwinn said. “They failed to look at any of it.”

Hayes’ oldest daughter, Robin Altman, didn’t immediately question the suicide ruling. But she said that changed as time passed and the shock wore off.

Altman recalled arriving at the Northfield house the night of her mother’s death.  

“Nothing looked right,” she said.

Hayes was found dead on the floor of her bedroom.

Police determined she used an extension cord to strangle herself. But Alliance believes evidence shows Hayes couldn’t have died that way.

“You may have facilitated someone just getting away with murder,” said Dr. Bill Smock, a forensic physician who works with Alliance.

Meanwhile, “Backstory: Hidden Homicide” reporter Larry Potash had an off-camera conversation with Don Hayes, the second husband of Mary Ann Hayes. During their brief conversation, Don said his stepdaughter is “emotional.”

Steven Altman’s death raises ‘red flags’

Authorities said Steven, 21, hung himself from the boom of a forklift at his stepfather’s business on Chicago’s North Side. His death was ruled a suicide.

Steven had a history of depression and had spent time in a psychiatric institution. Chicago police didn’t open an investigation and no autopsy was performed. And now, experts are raising questions about his death, as well.

Smock reviewed the medical examiner investigator’s report on Steven’s death, as well as photographs from the scene, obtained by WGN Investigates.

“I think it’s very suspicious,” Smock said. “I’ve never seen a knot this complex, this unique in a suicide.”

Smock said he identified “three separate ligature marks on [Steven’s] neck.”

“That’s a huge red flag,” he said. “Whenever I see more than one ligature mark, it’s an assault or homicide until proven otherwise.”

Steven’s death remains classified as a suicide and is not currently under investigation.