CINCINNATI -- Donald Harvey, the "Angel of Death" who pleaded guilty to poisoning 24 patients at Cincinnati's Drake Hospital, has died, according to the Associated Press.

Harvey was hospitalized and on life support Wednesday and not expected to survive, according to a highly placed law enforcement official.

Harvey, 64, was beaten in his cell, state authorities said. He was incarcerated at Toledo Correctional Institution in Lucas County since 2008.

JoEllen Smith, spokeswoman for Ohio's prison system, said Harvey was found in his cell Tuesday.

Harvey's most recent mugshot from prison.

A crime report from the Ohio State Highway Patrol, which is investigating the assault, does not name the suspect.

In addition to the Drake killings between 1986 and 1987, Harvey claimed he killed 50 more people during the time he worked at the Cincinnati VA Hospital and Marymount Hospital in London, Kentucky -- and others he killed just because.

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Harvey, a hospital orderly, said he started killing out of mercy for terminally ill patients, then he just started to like it.

The killings at Drake Memorial Hospital stunned the Tri-State in the late 1980s.

He said he used cyanide most of the time because it was hard to detect. But a doctor doing an autopsy on one of his Drake Hospital victims caught a whiff of the poison, and authorities traced the killing to Harvey.

That might have been the end of the story -- one count of murder -- except for WCPO anchor Pat Minarcin. Minarcin's investigation revealed a serial killer.

Harvey admitted those Drake killings and a dozen others to escape the death penalty.

Ultimately, Harvey was convicted of 36 murders between 1970 and 1987. He was eligible for parole in 2043.

Editor's note: WCPO does not ordinarily use anonymous sources. However, WCPO staff members use anonymous sources in rare circumstances where such sources are the only way to obtain information vital to the public good. WCPO staff members have vetted these sources and believe the information they provide to be accurate and in good faith.