Relatives of the victims and Cincinnati area officials are trying to understand how a seemingly benign orderly could commit mass murder in a public hospital and almost get away with it.

By his own account, Donald Harvey poisoned or suffocated 21 patients at Daniel Drake Memorial Hospital between 1982 and early this year. He pleaded guilty to those killings and three others that had originally been considered natural deaths Tuesday after the Hamilton County prosecutor agreed not to seek the death penalty.

Harvey said in a televised interview Wednesday that he was driven by mercy to put his victims, who were for the most part chronically ill, "out of their misery."

But the psychiatrist who examined him for the prosecutor said Harvey was a "psychic monstrosity" who gratified himself by murdering helpless old people, mostly men. "He is a compulsive killer," said Dr. Emmanuel Tanay of Wayne State University, comparing Harvey to serial killer Theodore Bundy, now on Florida's death row.

Harvey's lawyer, William P. Whalen Jr., said the 35-year-old native of rural Kentucky privately confessed that he committed as many as 52 murders in Cincinnati and Kentucky over 16 years.

Harvey was sentenced to three consecutive life terms with the possibility of parole in 60 years.

The killings went undetected because Harvey singled out patients who were expected to die and almost unerringly chose victims who were not destined for autopsies, assistant prosecutor Joseph Deters said.

According to Deters, Harvey's methods left no conspicuous trace. He injected air into his victims' veins and laced others' food with arsenic, cyanide or rat poison. He pulled the plug on respirators and smothered patients in their beds.

A local television station reported that members of the Drake Hospital staff nicknamed Harvey "the Angel of Death" and had told superiors as early as last year that they suspected he might be connected to a string of sudden deaths.

But no firm link was established until a coroner smelled cyanide during an autopsy on John Powell, a traffic accident victim who died in March after months in a coma.

Police charged Harvey with killing Powell. The investigation went no further until June, when television station WCPO aired a report in which Drake hospital staff members, their identities concealed, told how Harvey frequently discovered deaths on his ward and joked about them. The hospital sources said they had told this to superiors, but saw no evidence of an investigation by the administration.

The county tried to confirm the report, but Harvey alone possessed the evidence needed to seal the multiple convictions that would expose him to the death penalty, Deters said. Officials said the scope of Harvey's eventual confession, which they corroborated in part by exhuming bodies, defied comprehension.

Deters said the hospital's conduct amounted to "a tragic case of stupidity."

A Drake hospital spokeswoman referred questions to a lawyer, whose receptionist said he would not comment.

Whalen said that Harvey was acting out of anger toward his male lover, Carl Hoeweler, when he poisoned Hoeweler's mother and father. The mother survived. Jealousy motivated Harvey to infect one of Hoeweler's female employes with hepatitis, and Harvey repeatedly gave Hoeweler nonlethal doses of poison to keep him at home, Whalen said.

Harvey confessed to dozens of unsuspected killings at a Cincinnati Veterans Administration hospital and at various Kentucky hospitals, where he had worked. Whalen said he did so because he "wants to go to prison with a clean slate, and, if you'll excuse the pun, knowing that there are no more skeletons out there."

The associate director of the Cincinnati Veterans Administration Medical Center, Robert Sabin, said officials knew of no mysterious deaths there, but the Justice Department is investigating.

Harvey left the VA hospital, where he worked as a morgue attendant and cardiac-care assistant, amid suspicions that he had stolen tissue samples, Sabin said. He was facing disciplinary action for carrying a revolver when he resigned, Sabin said.

Tanay, the psychiatrist, said that Harvey was a troubled individual who was sexually abused by male relatives as a child and attempted suicide several times.

If officials at the VA hospital questioned Harvey's behavior, others who knew him saw no hint of a darker side.

"I'm looking at someone I never knew," said Lena Gabbard, Harvey's first grade teacher in Owsley County, Ky. She remembers Harvey fondly after almost 30 years as "a clean-cut, pretty boy who was never a disciplinary problem."

"He was the kind of a child that worked to be a teacher pleaser," Gabbard said.

Izella Kendrick remembered Harvey as a cheerful, pleasant young man who "always had a warm word" as he helped care for her chronically incapacitated husband. The 69-year-old widow said she was aghast to learn that Harvey killed him by pouring cyanide-laced orange juice down his gastric tube last September.