Irene Annie Graham was an 89-year-old woman whose hospitalization in Perris, California, became the beginning of a disturbing series of patient deaths later attributed to registered nurse Robert Rubane Diaz. Graham had been admitted to the intensive-care unit at Community Hospital of the Valleys on the evening of March 29, 1981, after experiencing chest pains following a burglary at her home.
She was suffering from congestive heart failure, and electrocardiogram readings indicated that she was having an ongoing heart attack. Despite those serious medical problems, a nurse caring for Graham described her vital signs as stable and her heartbeat as generally regular during the first several hours she was in the unit.
The overnight nursing shift began at approximately 11:00 p.m., and Diaz was one of three nurses working in the intensive-care unit. Graham was primarily assigned to nurse Dorothetta Ernest. Between about 4:30 and 5:00 a.m., while Ernest was away on a meal break, Diaz told another nurse that Graham was having problems and asked that Ernest be called back. When Ernest returned, she found Graham apparently sleeping while Diaz was injecting something into Graham's intravenous line. Diaz said Graham had developed ventricular tachycardia, a dangerously rapid heart rhythm, and told Ernest that he was giving her two bolus injections of lidocaine, a medication commonly used to treat certain abnormal heart rhythms.
Ernest contacted Graham's doctor and reported the apparent heart-rhythm problem. The physician ordered a continuous lidocaine infusion, which was started at approximately 5:30 a.m. About 15 minutes later, Graham suddenly screamed and went into an extraordinarily violent seizure. Ernest later described it as resembling a grand mal epileptic seizure but even more severe. Graham then stopped breathing, followed rapidly by cardiac arrest. Hospital personnel attempted to resuscitate her, but the efforts were unsuccessful. She was pronounced dead at approximately 6:15 a.m. on March 30, 1981.
At first, Graham's death did not appear to be a homicide. She was an elderly cardiac patient with congestive heart failure and evidence of a heart attack, circumstances that provided an apparent natural explanation for her death. The significance of her violent seizure only became clearer as additional patients in the same intensive-care unit began suffering remarkably similar episodes. During the next several weeks, patients experienced sudden seizures followed by respiratory and cardiac arrest, frequently during shifts when Diaz was working. The unusual pattern eventually brought the deaths under investigation.
When Graham's case was later examined as part of the homicide investigation, prosecution experts reported extremely high concentrations of lidocaine in her tissues. A cardiology expert testified that her medical findings could have resulted from an injection of roughly 500 to 1,000 milligrams of lidocaine into her intravenous line shortly before the seizure. A prosecution pathologist ultimately concluded that Graham died from lidocaine poisoning, with her underlying heart disease contributing to her death. Diaz's defense disputed that interpretation, arguing that her severe cardiac disease and therapeutic use of lidocaine could account for both the drug levels and her medical collapse. The courts ultimately accepted the prosecution's evidence and concluded that Graham had received a fatal overdose.
The investigation grew far beyond Graham's death. As authorities examined the cluster of deaths at Community Hospital of the Valleys, patient records were seized and bodies were exhumed for toxicology examinations. The hospital's intensive-care unit eventually closed. Investigators discovered syringes associated with patients that were labeled as containing ordinary one- or two-percent lidocaine solutions but were later found to contain concentrations exceeding 20 percent. Police also obtained a warrant and searched Diaz's home on May 1, 1981, recovering syringes, lidocaine packaging and vials containing the drug. Prosecutors later presented these findings as part of a larger circumstantial case showing that someone had deliberately substituted highly concentrated lidocaine and administered lethal doses to patients.
Diaz became the central suspect because of his presence during the suspicious deaths, his access to the patients and medication, and the toxicological and medical evidence. After leaving the Perris hospital, he went to work at San Gorgonio Pass Hospital in Banning, where another patient died after developing similar symptoms while Diaz was working. Investigators ultimately focused criminal charges on 12 deaths at the two Riverside County hospitals, including Graham's. Diaz was arrested at his Apple Valley home on November 23, 1981, and charged with multiple counts of first-degree murder.
Diaz denied being a murderer and challenged the scientific evidence against him. His case eventually went to trial in Riverside County Superior Court beginning October 31, 1983. He waived his right to have a jury determine his guilt, leaving Superior Court Judge John Barnard to hear the lengthy and medically complex case. Prosecutors argued that Diaz had deliberately injected critically ill patients with massive overdoses of lidocaine, while the defense maintained that the deaths could be explained by the patients' serious illnesses, legitimate drug treatment or other medical causes.
On March 29, 1984, Judge Barnard found Diaz guilty of all 12 first-degree murders, making Graham one of the patients for whose killing he was formally convicted. The court also found the multiple-murder special circumstance to be established. On April 11, 1984, Barnard rejected a defense request for life imprisonment without parole and sentenced Diaz to death in California's gas chamber. The California Supreme Court later reviewed the extensive medical and circumstantial evidence and, in 1992, affirmed the judgment, concluding that substantial evidence supported findings that the patients had died from lidocaine overdoses administered by Diaz.
Diaz was never executed. He remained under a death sentence for more than two decades while continuing to maintain his innocence. On August 11, 2010, he died of natural causes while still a condemned California prisoner. Graham's death, initially capable of being mistaken for the natural loss of a gravely ill cardiac patient, ultimately became one of the central cases in a prosecution that established a deliberate pattern of hospital killings and resulted in Diaz's conviction as the person responsible.
