CHICAGO (CBS) — The death of an aide to Illinois Congressman Dan Lipinski has been ruled a homicide.

The Cook County medical examiner’s office said Wednesday that Marianne Viverito suffered multiple stab wounds.

READ MORE: Woman Questions COVID-19 Clinic After Receiving Results Before Testing

Viverito’s body was found Tuesday in the basement of her Oak Lawn home after police received a request for a well-being check from an out-of-state police agency. The agency indicated a woman may have been injured in a domestic fight.

Police have said Viverito’s death was an “isolated incident” and the public wasn’t in danger. Police said they had a suspect in the case, but wouldn’t release other details.

Louis Viverito, a former state senator and father of the 55-year-old congressional aide tells WBBM that he believes one of his grandsons is responsible and says the mental health system failed in this case, WBBM’s Steve Miller reports.

For 10 years, Marianne Viverito, a divorced mother of two adult sons, worked for Congressman Dan Lipinski, D-Chicago.

READ MORE: 17-Year-Old Shot In Hyde Park

Her father says he doesn’t know exactly what happened, but he believes his 27-year-old grandson is responsible.

“He was a sweet, nice, loving boy that would tell me, ‘Grandpa, I’m not feeling good. I’m hallucinating. I can’t concentrate,’” he says. “I said, ‘You’ve got to tell the psychiatrist.’ He said, ‘I did, Grandpa.'”

Viverito says he can’t blame the psychiatrists or the social workers because they’re overworked.

“The only thing I can tell you is, there’s a big, big void in mental health,” he said.

He said her younger son was in Las Vegas when his mother’s body was found.

MORE NEWS: Two Hospitalized After Shooting In Portage Park

(Copyright 2017 The Associated Press contributed to this report. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)