Robert Diaz had always wanted to be a doctor, but eventually he had to settle for nursing. Diaz was clearly not happy with just being a nurse though. In April 1981, an anonymous caller telephoned the San Bernadino County coroner and claimed that Diaz had killed about 19 patients at a hospital in Perris, Calibornia. An investigation begun, and it was soon clear that Diaz had in fact killed several patients.

When the patients in question had died, Diaz had been the only nurse on duty. Accorded to records and co-workers, Diaz had been predicting the time that some patients would die almost exactly. He had even been seen giving some patients injections shortly before their deaths. Some medical records on the deceased patients were missing also, and Diaz had had access to these records. In the one night he had worked at a different hospital, San Gregorio Pass Hospital, one patient had died under his care.

In November 1981, Diaz was arrested and charged with the deaths of 12 patients. His trial did not take place until March 1984, and before then the bodies of his victims were exhumed, and samples taken. These samples showed that they had died of an overdose of the drug Lidocaine. When Diaz’ home was searched some Lidocaine was found, along with needles and large samples of morphine.

Robert Diaz was found guilty on 29th March 1984, and sentenced to death.