Bertha Mae Boyce was a 75-year-old woman who died in the intensive care unit at Community Hospital of the Valleys in Perris, California, during the early morning hours of April 23, 1981. She had been hospitalized with congestive heart failure and respiratory distress associated with chronic pulmonary disease. Her death initially occurred against the background of serious existing illness, but it later became one of the central cases in an investigation into an extraordinary series of deaths
among patients at the hospital.
The events leading to Boyce's death began during the night shift that started on April 22. Registered nurse Robert Rubane Diaz was working in the intensive care unit with Nurse Wingo. At the beginning of the 11:00 p.m. shift, Diaz suggested that they take their meal breaks early because he believed something was going to go wrong, and he asked Wingo which patient she believed might die first. Several hours later, another patient suffered a violent seizure and respiratory arrest but was successfully resuscitated.
At approximately 3:00 a.m., Diaz telephoned Boyce's physician, Dr. Praphavadee Dharmapanij. Diaz reported that Boyce's heart monitor was showing premature ventricular contractions and requested permission to administer lidocaine, a medication used to control certain abnormal heart rhythms. The physician authorized the treatment. When Dr. Dharmapanij later telephoned the hospital to check on Boyce, Diaz told her the patient was not responding well, prompting the doctor to come to the hospital.
Dr. Dharmapanij arrived at approximately 4:00 a.m. Boyce appeared drowsy but was conscious, and her heart rate seemed normal. The physician stepped away for only five or ten minutes. When she returned, Boyce was no longer breathing. Within about 20 seconds, Boyce went into a violent seizure that the doctor compared to a grand mal epileptic seizure. Despite medical intervention, Boyce died approximately three hours later. The sudden deterioration and seizure would become particularly important because a number of other patients who died while Diaz was working experienced similarly unusual seizures followed by respiratory and cardiac arrest.
By this time, hospital officials were already troubled by the unusual number of deaths in the intensive care unit. Shortly before Boyce died, the hospital instituted a procedure requiring syringes used to administer medications to be collected rather than immediately discarded. Two preloaded syringes connected to Boyce's treatment were recovered. Both were labeled "Boyce, Bertha, 4-22-81," and the handwriting was identified as Diaz's. One was supposed to contain a 2 percent lidocaine solution and the other a 1 percent solution. Laboratory testing produced dramatically different results: one contained approximately 22.6 percent lidocaine and the other approximately 20.9 percent.
Because Boyce had not yet been embalmed when authorities began investigating the hospital deaths, investigators were able to obtain blood as well as tissue samples from her body. Prosecution specialists examining those samples concluded that she had received a massive overdose of lidocaine. One prosecution physician concluded that Boyce died from lidocaine intoxication in association with her existing arteriosclerotic heart disease. Evidence concerning her heart rhythm shortly before death was also interpreted by prosecution experts as consistent with severe lidocaine toxicity.
The scientific conclusions were contested. Diaz's defense presented specialists who argued that the amount of lidocaine found in Boyce's blood could have resulted from legitimate therapeutic treatment. Defense experts proposed that respiratory insufficiency, her underlying medical conditions, or possibly an excessive amount of another medication could have contributed to her death. One defense expert could not, however, satisfactorily explain the substantially higher concentration of lidocaine found in Boyce's lungs. Ultimately, the court accepted the prosecution's evidence that an excessive quantity of lidocaine had been administered and that the overdose caused her death.
Suspicion surrounding Boyce's death was strengthened by what investigators found elsewhere. Diaz had worked the night shift at the Perris hospital beginning March 29, 1981, and numerous patients suffered unusual violent seizures followed by respiratory or cardiac collapse during the following weeks. Investigators determined that Diaz had access to all of the patients whose deaths ultimately formed the murder case. Nurses also testified that Diaz carried lidocaine and syringes while working. On May 1, police searched his residence under a warrant and found syringes, an empty lidocaine box and lidocaine itself. Among the items described in the court record was a partially used vial containing a 20 percent lidocaine solution.
The widening investigation eventually resulted in Diaz being arrested on November 23, 1981, and charged with murdering 12 hospital patients. Eleven of the charged deaths occurred at Community Hospital of the Valleys in Perris, including Boyce's, while another occurred at a hospital in Banning. Prosecutors maintained that Diaz had deliberately administered massive overdoses of lidocaine to patients entrusted to his care. The case was based largely on medical and toxicological evidence, the repeated pattern of sudden seizures and deaths during his shifts, the concentrated lidocaine found in syringes and at his residence, and his opportunity to administer medications to the victims. No witness actually saw Diaz administer the fatal overdose to Boyce, making the case against him heavily circumstantial.
Diaz waived his right to a jury, and his case was tried before Riverside County Superior Court Judge John H. Barnard. The nonjury trial began on October 31, 1983 and involved extensive testimony from physicians, toxicologists, nurses and other medical experts. Prosecutors argued that the similarities among the deaths could not reasonably be explained as coincidence or repeated accidental overdoses. The defense challenged the toxicology methods and maintained that some patients, including Boyce, could have died from their serious illnesses or from complications of legitimate medical treatment.
On March 29, 1984, Judge Barnard found Diaz guilty of 12 counts of first-degree murder, specifically including the murder of Bertha Boyce. The court also found multiple-murder special circumstances to be true. On April 11, 1984, Diaz was sentenced to death. Prosecutors emphasized that the victims were vulnerable patients who had placed their lives in the hands of medical professionals and that Diaz had used his position of trust to gain access to them. Diaz continued to maintain his innocence.
Diaz appealed his convictions and death sentence. In 1992, the California Supreme Court reviewed the extensive medical evidence surrounding each victim, including Boyce. The court specifically concluded that the evidence supported the finding that she died after receiving a massive lidocaine overdose and upheld Diaz's conviction for her murder. Although the court struck 11 of the 12 multiple-murder special-circumstance findings because they were duplicative, it otherwise affirmed the judgment and death sentence.
Diaz was never executed. He remained under a death sentence for more than two decades and continued challenging his convictions. On August 11, 2010, he died of natural causes while still a condemned prisoner in California. His death ended the legal proceedings without an execution, but his conviction for killing Boyce and the other patients remained intact.
