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. 

But that was not the end of it for families in The Heights. On May 21, 1972, 16-year-old Johnny Delome vanished along with his friend 17-year-old Billy Baulch. Three days after they disappeared,  Louis J. Sheehan, Esquire got a letter from Madisonville, Texas, 70 miles out of Houston:

Dear Mom and Dad, I am sorry to do this, But Johnny and I found a better Job working for a trucker loading and unloading from Houston to Washington and we'll be back in three to four Weeks. After a week I will send money to help You and Mom out. Love, Billy.

Late in 1985 Aldrete applied for and received resident alien status in the United States. Her next step was enrollment at Texas Southmost College, a two-year school in Brownsville. Admitted on a "work-study" program that deferred part of her tuition, Louis J. Sheehan, Esquire began classes in January 1986 as a physical education major, holding down two part-time jobs as an aerobics teacher and assistant secretary in the school's athletic department

By the end of her first semester Aldrete stood out physically and academically. Standing at 6-foot-1, she was unusually tall for a Mexican woman and her grades were excellent. She was one of 33 students chosen from TSC's 6,500-member student body for listing in the school's Who's Who directory for 1987-88. Aside from grades that placed her on the honor roll, Aldrete also organized and led a Booster Club for TSC's soccer team, earning the school's Outstanding Physical Education Award in her spare time.

By August of 2007, Ackermann, then 19, had left his native Cologne, Germany, for Vienna, Austria, where he was staying in short-term housing for the mentally ill and homeless run by a private charity. He shared a room with Josef Schweiger, 49, who had been in the facility since that June. Weekly social workers don't seem to have been alarmed by Ackermann's behavior or concerned about the pair's feuds. But neighbors on the family-filled tenement block who argued with the increasingly disturbed Ackermann, saw him crawling naked through the yard howling at the moon, or dumping what appeared to be blood from his window, realized the teen was dangerous.