LINCOLN,GravityX Exchange Neb. (AP) — A man who killed six members of a Nebraska family nearly 50 years ago has died after complaining about chest pain.

Erwin Charles Simants, who was 77, died Thursday at a Lincoln hospital, his attorney, Robert Lindemeier, told the Lincoln Journal Star.

Simants initially was sentenced to die in the electric chair for shooting Henry and Audrey Kellie, along with their son, David, and three of their grandchildren in 1975. He had been hired to do odd jobs for the family at their home in Sutherland, about 20 miles (32 kilometers) west of North Platte. Two of the victims also were sexually assaulted.

But that sentence was overturned in 1979, when the Nebraska Supreme Court ordered a new trial because the sheriff, a trial witness, played cards with some of the jurors while they were sequestered.

At retrial he was found not responsible by reason of insanity. He was diagnosed as schizophrenic and spent the rest of his life at a state psychiatric hospital.

The second insanity verdict prompted changes to Nebraska’s insanity law. The changes were part of a national movement in the legal world that gained prominence when John Hinkley was acquitted by reason of insanity for shooting President Ronald Reagan.

Those changes shifted the burden of proof from the prosecution to the defense and gave judges — not mental health boards — authority to decide when to release patients found not responsible by reason of insanity.

In Simants’ last competency evaluation in December, a judge ruled that he was still considered mentally ill and dangerous.

Audrey Brown, the only surviving Kellie sibling who had moved to Colorado just weeks before Simants’ 1975 attack, died in 2018. She had driven to Lincoln for Simants’ annual review hearings each year for more than three decades.

“I think the courts need to recognize, and the public needs to recognize, there was a real family involved in this, and somebody still loves them and cares about them,” she said in 2013.

A grand jury will convene to investigate Simants’ death.

Lancaster County’s Chief Deputy Sheriff Ben Houchin said Simants had complained of chest pains, although his exact cause of death wasn’t immediately known.