The mother of a Utah State Prison inmate says the prison is responsible for the death of her mentally ill son, who spent his last 16 hours of life strapped to a restraining device.

"He didn't die of a heart attack . . . he was induced to a heart attack," said Angela Armstrong, the mother of inmate Michael Valent, 29, who died Thursday. "He's gone, and the reason he is gone is because we have become archaic and barbaric in our society."Armstrong spoke to the media during a press conference called by the American Civil Liberties Union Monday to announce an investigation that may result in litigation against the use of "barbaric" restraining devices used throughout Utah prisons.

The "restraint chair" restrains an inmate in a sitting position with two wide straps crosswise on the body. Cuffs hold the inmate's arms down at his sides and his feet together on the floor.

Valent's death "has brought to the forefront" the increasing use of restraining devices as treatment or punishment for mentally and non-mentally ill inmates, said ACLU attorney Jensie Anderson.

"This is an issue we've been investigating, and we're saddened that in the middle of our investigation something as heinous and tragic as this could happen," Anderson said. Although the ACLU has no proof that Valent died as a result of being strapped to a restraining device, she said her office is "aggressively investigating the use of the chair," which has been used in Utah for about a year.

Corrections spokesman Jack Ford confirmed that Valent had been on the restraint chair for 16 hours but denied that it caused his death. Valent was put on the chair to prevent him from hurting himself after he would not stop banging his head, arms and feet against prison walls, he said.

Prison psychiatrist David L. Egli recommended Valent be bound in the chair until he was no longer considered a danger to himself or others, said Lane McCotter, executive director of the Utah Department of Corrections. A prior consent decree in a prison inmate case prevented the doctor from forcing Valent to take his medications.

"The chair had nothing to do with his death," Ford said. "He did not die on the chair. He was on the chair because he was suicidal."

The only way to prevent Valent from killing himself was to put him in some sort of restraining device, and the chair is one of the "least offensive ways of restraining someone," he said.

"The problem is that he was a threat to himself and a threat to others," Ford said.

As is routine in deaths at the prison, the Salt Lake County Sheriff's Office is investigating Valent's death. Prosecutor Richard Shepherd said his office began collecting reports about the death Monday but said it will take at least a week to determine if there was any criminal negligence.

Valent was convicted in 1987 of stabbing his grandmother to death in Price. Armstrong said Valent was diagnosed with schizophrenia at 19, then spent three years at the Utah State Hospital before being transferred to the prison in 1990.

Thursday, Valent collapsed while in the shower after being removed from the restraint chair.

The initial autopsy indicated he died of a pulmonary embolism - a blood clot hitting his heart and essentially causing a heart attack. Ford said the blood clot may have been caused by a self-inflicted blow.

Armstrong was told Valent died of a "massive heart attack," but she did not know he had been on a restraining device until Monday morning.

"They never told me anything," she said.

Among the ACLU's concerns are complaints that in the past inmates have been left on the restraint chair for more than five consecutive days and that restraint devices may be a growing trend of "management" among Utah corrections facilities.

"We're finding harsher and harsher ways to deal with people that may not belong in a prison to begin with," said ACLU executive director Carol Gnade. "(The restraint chair) just seems like the most barbaric thing that someone can sit in for a period of time."

Valent was among approximately 15 percent of inmates with serious mental disabilities at the Utah State Prison, said Fraser Nelson, executive director of the Legal Center for People With Disabilities. When medication fails, other less restrictive methods to deal with them include padded cells or suicide watch cells, she said.

"If he was throwing himself around a wall, I would much rather he was kept in a padded cell," Armstrong said. She hopes her son's death will end the use of restraining devices.

"I'm hurt, very hurt. I think I know what the blessed mother went through when she saw her son crucified. I think this is another type of crucifixion. Hopefully his death won't be in vain."