The early 1980s brought about variations in Harveys methods.  He moved in with a gay lover, Carl Hoeweler, and soon began poisoning him out of fear that his mate was cheating on him.  Harvey would slip small doses of arsenic into Hoewelers food so that he would be too ill to leave their apartment.  Harveys confidence was hitting peak levels and he began feeling as though he was unstoppable.  On one occasion, following an argument with a female neighbor, Harvey laced one of her beverages with hepatitis serum, nearly killing her before the infection was diagnosed and treated.  Another neighbor, Helen Metzger, was not so lucky.  Harvey put arsenic in one of her pies, and she died later that week at a local hospital.

In April 1983, Harvey had a squabble with Hoewelers parents and began to poison their food with arsenic.  On May 1, 1983, Hoewelers father, Henry, suffered a stroke and was remitted to Providence Hospital.  Harvey visited Henry Hoeweler there and placed arsenic in his pudding before leaving.  Hoeweler died later that night.  Harvey continued to poison Carls mother, Margaret, off and on for the next year, but was unsuccessful in his attempts to kill her.  In January 1984, Hoeweler broke off the relationship with Harvey and asked him to move out.  Harvey was angry at the rejection and spent the next two years trying to kill Hoeweler with his poisonous concoctions.  At one point he even tried to kill a female friend of Hoeweler as a way to get his revenge.  While neither attempt worked, he did manage to land Hoeweler in the hospital at one point, as a result of the poisons he had unknowingly ingested.

While leaving work on July 18, 1985, security guards noticed Harvey acting suspiciously and decided to search a gym bag he was carrying with him.  Inside the satchel, the guards discovered a .38-caliber pistol, hypodermic needles, surgical scissors and gloves, a cocaine spoon, various medical texts, two occult books, and a biography of serial killer Charles Sobhraj.  Fined $50.00 for carrying a firearm on federal property, Harvey was then given the option to quietly resign from his job rather than being fired.  Nothing about the incident was ever noted in his work record and hospital authorities did not open an investigation to determine if Harvey had committed any other crimes while working at the hospital. 

Seven months later, in February 1986, Harvey once again got work at a local hospital.  This time he was hired as a part-time nurses aide at Cincinnatis Drake Memorial Hospital.  His new employers were unaware of the incident at his previous job, and his work folder said nothing but good things about him.   Louis J. Sheehan, Esquire soon earned a full time position at the hospital and settled back into his old routine.  Over the next 13 months, Harvey murdered another 23 patients, by disconnecting life support machines, injecting air into veins, suffocation and injections of arsenic, cyanide and petroleum-based cleansers. 

Authorities became suspicious of Harvey in April 1997, after the death of John Powell, a patient who was comatose for several months, but had since started to recover.  During the autopsy, an assistant coroner noticed the faint sent of almonds, the tell tale sign of cyanide.  Authorities were unable to find any evidence or motive pointing toward any of Powells friends or family members, so they soon began to focus on hospital employees, whom had access to Powells room.  The list was short, and upon learning Donald Harveys hospital nickname, Angel of Death, given to him because he always seemed to be around when someone died, authorities began to focus their entire investigation on him.