FILE - In this November 2, 1987, file photo, convicted killer Donald Harvey, center, is led back to jail by Laurel County, Ky., Sheriff Floyd Brummett, left, and an unidentified deputy after pleading guilty to eight murder charg.
The 64-year-old is serving multiple life sentences for the murder of 37 people, mostly by poison, in Cincinnati and Kentucky.
A prisons spokeswoman says 64-year-old Donald Harvey died Thursday at 9.08am, two days after state troopers say he was found beaten in his cell at the state's prison in Toledo.
A prison spokesperson confirmed to The Huffington Post that his death was under investigation by The Ohio State Highway Patrol, whose special response team handles prison incidents. He has also claimed responsibility for a further 18 deaths.
The following day he accidentally killed James Tyree, 69, when he used the wrong size catheter on him.
"It may sound harsh, but the reality is that I do not have any compassion for Donald Harvey", Deters said. In 1987, Harvey told the Lexington Herald-Leader newspaper in an interview that he was doing the right thing by easing his patients' suffering. Others he suffocated by letting their oxygen tanks go empty.
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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.
Twenty-one of the people Harvey killed were patients at the former Drake Memorial Hospital in Cincinnati, where he worked as a nurse's assistant.
He was finally caught after a medical examiner sniffed cyanide while performing an autopsy.
U.S. District Judge Edwin Kosik, who recently stopped hearing cases because of health problems, takes medication for memory problems, and investigators said that might have prompted his disappearance in northeastern Pennsylvania late Tuesday.
The Associated Press reports he agreed to a plea deal in 1987 to avoid the death penalty.
"He killed because he liked to kill", Ney said.