Dr. Peter Heinbecker always wondered what would happen to his patient, Mike Valent, after the deeply disturbed man was transferred from the state mental hospital to prison.

Valent, he knew, was capable of terrible violence when in the grip of schizophrenic dementia. In 1987, he had murdered his grandmother in Price after the voices in his 19-year-old head told him to.But Valent, when properly medicated, posed little threat, said Heinbecker, a psychiatrist who has worked in the forensic ward at the Utah State Hospital in Provo for nearly two decades.

After the murder, Valent spent three years at the hospital and earned a job in its snack bar, where he was popular with patients and staff.

"I considered him my good friend," the doctor said.

Which, for Heinbecker, made Valent's death March 20 at the Utah State Prison, after 16 straight hours in a restraining chair and in the depths of his madness, all the more outrageous and unnecessary.

"It never would have happened had he remained here," Hein-beck-er said. "He never should have gone to prison in the first place.

"I have always realized that treatment out there for the mentally ill was terrible," he said. "It's brutal. . . . Their attitude is punishment. They're there to punish. They're not there to treat."

But Utah lawmakers decided, in the wake of the 1981 assassination attempt on President Reagan, that the criminally insane are criminals first and foremost, regardless of the role their illness may have played.

Civil libertarians, psychiatrists and attorneys have debated the issue ever since.

Valent's death, and prison officials' acknowledgment they have used the chair nearly 100 times on the mentally ill in the past 18 months, have focused attention on the treatment of an estimated 400 seriously mentally ill men and women who dwell behind prison bars.

The main prison in Draper has just 35 beds for the mentally ill in its hospital wing. Another 50 or so are at the state hospital.

To some degree, Heinbecker's concerns are shared by the American Civil Liberties Union and the Disability Law Center, which are looking into more than a dozen complaints by inmates who claim they were forcibly restrained in the chair or on a restraining board.

Physical restraints, they say, are used too often and efforts to calm patients with drugs and therapy are not used often enough.

Worse, there is evidence the chair is used for punishment, in violation of the prison's own policies. Department of Corrections spokesman Jack Ford had cited at least three instances in which inmates were restrained for hours after they flooded their cells.

It's not that restraining devices are never used elsewhere. But it appears the Utah prison is too quick to resort to what clinicians generally consider a last resort, said the law center's Linda Priebe.

The state mental hospital does not have a restraining chair. When restrained, patients are "four-pointed" in a bed under constant supervision.

The hospital used restraints on its 76-patient forensic ward 31 times on seven patients in the past three months, said spokeswoman Janina Chilton. Each instance lasted no more than four hours, and one particularly disturbed patient accounted for more than half of them.

Ford said prison inmates have been "chaired" for as long as four or five days on end. The ACLU and DLC are cooperating on a planned lawsuit by an inmate who was strapped to a table for three months.

Corrections attorney Frank Mylar disputes any assertion that mentally ill inmates are abused, misdiagnosed or otherwise ill-treated at Utah State Prison. He said a federal decree makes forced drugging of inmates impractical.

And he defends the use of restraining devices, arguing that prison officials must have some way of dealing with abusive or dangerous inmates. Even so, he announced that the prison would discontinue use of the chair pending a policy review. Violent or self-destructive inmates will continue to be tied to restraining boards as the need arises, Mylar said.

But Mylar added that critics have to keep in mind the role of corrections, which, frankly, involves punishment of inmates.

"They're confined for punishment purposes," he said. "But there is also the rehabilitation and treatment goals, and there's the trying to help them to function within the system.

"If someone is out of control, it may make sense sometime to . . . use some means to restrain," Mylar said.

Physical restraints are often the only option available at the prison since therapeutic remedies are limited by a 1981 federal court consent decree setting out specific circumstances when inmates can be force-medicated, Mylar said.

Mylar and other Corrections officials maintain the order is so cumbersome and poorly constructed it makes it virtually impossible for prison doctors to medicate an inmate without consent. The department has filed a petition with the court to have the decree vacated.

But Priebe, the DLC lawyer who specializes in mental-health issues, says Mylar and the prison are laboring under a narrow and misguided reading of the decree. They are confusing short-term, emergency treatment - clearly provided for in the decree - with a later decision to seek long-term, forced medication.