Full opinion text
Opinion KENNARD, J. This is an automatic appeal from a judgment of death. (Pen. Code, § 1239, subd. (b).) After defendant Robert Rubane Diaz waived his right to a jury trial, the trial court convicted him of 12 counts of first degree murder (§ 187), and found to be true 12 multiple-murder special-circumstance allegations (§ 190.2, subd. (a)(3)). We shall order 11 of the 12 special-circumstance allegations stricken as duplicative, but otherwise affirm the judgment. I. Facts On March 29, 1981, defendant, a registered nurse, began work on the night shift in the cardiac care/intensive care unit (ICU) at Community Hospital of the Valleys (CHOV) in Perris, California. In the next three and one-half weeks, at least thirteen patients on the night shift suffered violent seizures, which were generally followed by cardiac and respiratory arrest. Nine of these patients died. The nurses who had observed the seizures described them as being similar to grand mal seizures suffered by epileptics; none of the nurses had ever seen such symptoms in cardiac patients. Following the closure of the ICU at CHOV, defendant accepted employment at San Gorgonio Pass Hospital. Within three days, while defendant was on duty, a patient died at that hospital after displaying the same symptoms as those observed in the patients who had died at CHOV. Within a day or so, defendant was arrested and charged with murdering a total of 12 patients (including 2 in whom seizures were not observed). At trial, the prosecution contended that defendant had killed the 12 patients by injecting them with massive overdoses of lidocaine, a drug commonly used in hospitals to control rhythm disturbances in the heart. All but one of the deceased patients had been given therapeutic doses of lidocaine while in the hospital’s ICU. The prosecution’s evidence showed that defendant assisted in the care of the patients before their seizures, and thus was in a position to administer fatal doses of lidocaine; that on several occasions defendant exhibited unusual behavior on nights when patients died; that the patients’ symptoms were consistent with having been given large overdoses of lidocaine; that the patients’ tissues or blood had unusually high concentrations of lidocaine; that syringes containing high concentrations of lidocaine were found in the hospital; and that lidocaine was found in defendant’s home. The defense theorized that some of the deaths resulted from natural causes, while others were caused by adverse reactions to medications administered for therapeutic purposes. Although the deceased patients had suffered from serious medical problems, many of them were not regarded as terminally ill. The evidence presented at trial does not suggest that the deaths were “mercy killings"; the prosecution did not argue such a theory at trial, nor did it suggest any other motive for the slayings. II. Guilt Issues A. Motion to Suppress Evidence On May 1,1981, after obtaining a search warrant, police officers searched defendant’s house and seized a number of items, some of which (syringes, an empty lidocaine box, and a vial containing lidocaine) were used against defendant at trial. Defendant unsuccessfully moved to suppress the seized items on several grounds, one of which was that the affidavit supporting the search warrant contained material misrepresentations and omissions. Defendant renews that argument here. The affidavit supporting the search warrant was prepared by Marshall Tolford, an investigator with the Riverside County District Attorney’s office. A summary of the 10-page affidavit follows. A confidential informant told the Riverside County District Attorney’s Office that 17 patients had died at CHOV between March 8 and April 14, 1981, and that the circumstances surrounding the deaths were “identical in many respects.” As described in the affidavit: “[A]ll patients suffered severe seizures prior to death. The patients suffered respiratory arrest, blood drawn prior to death was acidic and ... the patients were extremely blue from the chest area up.” Investigator Tolford, assisted by Riverside coroner’s investigator Michael Worthington, obtained Riverside County Health Department records, which showed that 24 patients had died at CHOV between March 8 and April 20, 1981. Worthington told Tolford that CHOV usually had three deaths per month. Because the death records listed myocardial infarction (heart attack) as the cause of death for most of the patients, Tolford became suspicious. The investigation revealed that the bodies of six of the patients who had recently died at CHOV had not yet been buried or cremated. Autopsies were performed on all six. Toxicological studies established lethal quantities of lidocaine in two of the six bodies. The pathologist who had performed the autopsies of the six patients told Tolford that an overdose of lidocaine would be accompanied by “several symptoms including seizures, respiratory arrest, a bluish tint to the upper torso of the body and acidic blood.” This led Tolford to examine 24 patient records that the police had seized from CHOV. Tolford discovered that defendant “did in fact attend every patient who died exhibiting these symptoms [seizures, acidic blood, respiratory arrest and a bluish tint to the upper torso] in the intensive care unit,” and that all of these patients had died in the hospital’s ICU. Tolford also learned that defendant had stopped working at CHOV on April 23, 1981, the day after police seized the patient records, and immediately found employment at San Gorgonio Pass Hospital. There, two patients died on the night of April 24-25, while defendant was on duty. Medical records showed that these two patients suffered seizures and respiratory arrest, and that they had a bluish tint to the upper torso. Investigator Tolford then interviewed Donna MacDonald, a licensed vocational nurse (LVN) working at CHOV. MacDonald said she and defendant had become known as the “deadly duo,” because a number of patients had died in the hospital’s ICU while they were working the same shift. Because all of those patients exhibited similar symptoms at the time of death, MacDonald suspected a connection between the deaths and the medication defendant administered. MacDonald recalled one occasion when defendant handed her a syringe containing lidocaine and asked her to inject it into patient Castro. Because of her suspicions, MacDonald did not do so. The syringe was later sent to the manufacturer, Abbott Laboratories, which reported: the syringe “had been tampered with, with lab results indicating a concentration slightly below standard concentration”; that two other syringes from CHOV containing lidocaine had also been tampered with, and had concentrations much higher than that stated on the packaging; and that the tampering occurred after all three syringes had left Abbott Laboratories, but before the lidocaine was administered to the patients. In an interview with investigator Tolford, defendant mentioned he had kept notes concerning the deaths of the patients. Defendant referred to these notes during the interview, but retained possession of them. In a second interview the next day, defendant claimed he did not know where his notes were. Tolford further stated in his affidavit that according to the medical records of four of the deceased patients (Boyce, Bayless, Patton and Swanson) whose blood samples contained lidocaine, these patients had “never” been prescribed lidocaine. Defendant asserts that investigator Tolford’s affidavit was deficient in four respects: (1) it inaccurately described statements that Nurse MacDonald made to Tolford; (2) it falsely stated that lidocaine was never prescribed to patients Boyce, Bayless, Swanson and Patton; (3) it falsely stated that CHOV had an abnormally high death rate between March 9 and April 20, 1991; and (4) it falsely stated that defendant attended all of the ICU patients who died after exhibiting symptoms of an overdose of lidocaine. Under the law applicable to this case, a defendant may seek to suppress evidence on the ground that the affidavit supporting the search warrant contained inaccurate statements. If, however, the affiant acted reasonably in including the misstatements in the warrant application, no sanction is imposed. If the affiant was negligent, or unreasonably believed the statements to be true, the reviewing court must correct the inaccurate information and “retest” the reformulated affidavit for probable cause. And if the affidavit contained reckless falsehoods or deliberate lies, the warrant must be quashed, regardless of whether the false statements were necessary to establish probable cause. (People v. Kurland (1980) 28 Cal.3d 376, 385-386 [168 Cal.Rptr. 667, 618 P.2d 213]; People v. Cook (1978) 22 Cal.3d 67, 75 [148 Cal.Rptr. 605, 583 P.2d 130]; Theodor v. Superior Court (1972) 8 Cal.3d 77, 100-101 [104 Cal.Rptr. 226, 501 P.2d 234].) With these rules in mind, we consider defendant’s challenge to the affidavit. 1. Statements by Nurse MacDonald Defendant contends that investigator Tolford inaccurately described in his affidavit certain information that Nurse MacDonald had given to him. At the hearing to suppress evidence, defendant introduced tape recordings of the only two interviews Tolford had conducted with Nurse MacDonald before preparing the affidavit in support of the search warrant. MacDonald’s statements in these interviews are inconsistent with those statements attributed to her in Tolford’s affidavit in three respects: (1) contrary to the affidavit, MacDonald did not say she was suspicious of defendant or thought there was a connection between the medication defendant had administered to the patients at CHOV’s ICU and their subsequent deaths; rather, she said she had no opinion about the cause of the deaths; (2) although the affidavit said MacDonald had told Tolford that she and defendant were referred to as the “deadly duo” because of the number of patients who had died at CHOV’s ICU while the two were on duty together, McDonald had not made such a statement to Tolford; and (3) contrary to the affidavit, MacDonald did not tell Tolford that the syringe defendant had asked her to administer to patient Castro contained lidocaine; instead, MacDonald said she did not want to inject the contents of the syringe because she did not know what was in it and she was not licensed to administer it. At the suppression hearing, investigator Tolford acknowledged the inaccuracy of his affidavit’s statement that Nurse MacDonald had told him that the syringe defendant handed her contained lidocaine. Tolford explained that the statement was based on his recollection of interviews with MacDonald, and that he believed the statement to be accurate when he included it in the affidavit. He thought MacDonald had told him that she suspected the deaths were linked to the medication that defendant had given the patients. He was not questioned about the affidavit’s statement that defendant and MacDonald were known as the “deadly duo.” The trial court concluded that although Nurse MacDonald did not explicitly make the statements attributed to her in Tolford’s affidavit, Tolford reasonably inferred them from the information MacDonald had given him. Defendant disagrees. He argues that because Tolford prepared the affidavit less than a day after he had interviewed MacDonald, at a time when her statements should have been fresh in Tolford’s mind, his inaccurate account of those statements is unjustifiable. Defendant asserts that if Tolford doubted the accuracy of his recollection, he should have checked the tape recordings of the interviews, which were in his possession. At the very least, defendant contends, Tolford made the statements with reckless disregard for the truth, and therefore the trial court should have quashed the search warrant. (People v. Kurland, supra, 28 Cal.3d 376.) We see no reason to disturb the trial court’s finding that the affidavit’s inaccuracies regarding the statements of Nurse MacDonald were neither negligent nor intentional. The investigation into the deaths of patients at CHOV was extremely complicated. There was also an urgent need to expedite the inquiry: although the ICU at CHOV had been closed, Tolford had information that suspicious deaths were taking place at the hospital where defendant had found employment after leaving CHOV. In preparing the lengthy affidavit in support of the search warrant, it was reasonable for Tolford to rely on his recollection of the interviews; he was not obligated to listen to tape recordings of each of the interviews in which he had obtained information that he incorporated into the affidavit. Tolford’s testimony at the suppression hearing provides substantial evidence to support the trial court’s finding that the inaccuracies in Tolford’s affidavit regarding statements by Nurse MacDonald were neither negligent nor intentional. 2. Lidocaine Prescriptions for Patients Boyce, Bayless, Swanson, and Patton Defendant argues that the search warrant affidavit was either deliberately false or made with reckless disregard for the truth in stating: “According to these [medical] records, lidocaine was never prescribed for administration to patients Boyce, Bayless, Patton and Swanson.” At the suppression hearing, defendant introduced medical records showing that lidocaine had been prescribed for patients Boyce and Patton, and that patient Swanson had been given therapeutic doses of lidocaine, apparently by nurses who were authorized to do so. (Patient Bayless’s records showed no prescription for lidocaine.) When Tolford was questioned at the suppression hearing about this inaccuracy in his affidavit, he explained that coroner’s investigator Worthington had examined the medical records of the four patients, and had told him that the records showed no prescription for lidocaine. Worthington corroborated Tolford’s testimony, explaining that he had based his conclusion that no lidocaine had been prescribed on the doctor’s order sheets in the patients’ files. Noting that Tolford had stated in the search warrant affidavit that both he and Worthington had reviewed the deceased patients’ medical records, defendant maintains it is “inherently unbelievable” that neither of them saw the lidocaine prescriptions in the patients’ charts. We have reviewed the medical records of patients Boyce, Swanson, and Patton. The only reference to lidocaine in Boyce’s lengthy record appears on the fifth page of six pages of progress notes. It reads: “PVC’s—abolished by lidocaine.” This cryptic notation seems to say that a doctor prescribed lidocaine for patient Boyce, but there is no reference to lidocaine in the five pages labeled “Physician’s Orders,” in the three pages labeled “Medication” or “IV Medication Sheet,” in the six pages of nursing notes, or in the two-page “Code Blue Sheet” listing the medications given Boyce during a life-threatening emergency. The evidence supports the trial court’s finding that Tolford’s failure to notice the single brief reference to lidocaine in Patient Boyce’s file was neither negligent nor intentional. Patient Swanson’s medical records contain no reference to lidocaine in the three pages labeled “Progress Notes,” or in the five pages marked “Physician Orders,” but two references to lidocaine, both clearly legible, appear on the two sheets labeled “Medication Record.” They show that on the morning he died Swanson was given a lidocaine injection at 5:15 a.m., followed by an intravenous infusion of lidocaine. Another reference to lidocaine, signed by defendant, appears in the nine pages of nursing notes. It states that Swanson was given an injection of lidocaine at 6:32 a.m. that same morning. Finally, on a strip of paper recording Swanson’s heartbeat were these notations: “Lidocaine 50 mg bolus,” and “Started Lidocaine Drip.” It appears that investigator Tolford overlooked these references to lidocaine because he and Worthington had examined only the physicians orders and progress notes, but not the medication record for Swanson. For purposes of this discussion, we will assume that Tolford and Worthington were negligent in failing to discover the references to lidocaine in patient Swanson’s file. With respect to patient Patton, his medical file contains many entries stating that Patton was prescribed lidocaine: twice in the physician’s orders, three times in the medication record, at least ten times in the nurses’ notes, once in the doctor’s progress notes, and on several of the strips of paper recording Patton’s heartbeat. Presumably, Tolford and Worthington looked only at the first, typed, page of the physician’s order sheet, and not at the second, handwritten page on which the physician’s orders appeared. The failure to discover that Patton was prescribed lidocaine was clearly negligent. As noted earlier, if a search warrant affidavit contains statements that are negligently inaccurate, we must excise those statements from the affidavit, and determine whether the remaining facts are sufficient to establish probable cause to search. (People v. Kurland, supra, 28 Cal.3d at p. 386.) Here, defendant does not dispute that the remaining portions of the affidavit establish probable cause to search defendant’s house. Rather, he argues that the affiant’s inaccurate statement that none of the three patients discussed above were prescribed lidocaine was not merely negligent, but was reckless or intentional, requiring that the warrant be quashed without adherence to the “excise and retest” procedure. We disagree. The statements in question were only a small part of a lengthy affidavit, of necessity drawn up in haste, recounting a rapidly moving investigation in a highly technical field. Under the unique circumstances of this case, some inaccuracies in the drafting of the affidavit were to be expected, and there is no reason to infer from the statements at issue by investigator Tolford an intent to deceive the magistrate. 3. Affidavit’s Statement Concerning High Death Rate at CHOV Investigator Tolford described as “abnormally high” the death rate at CHOV during the period March 8 to April 20, 1981, when the suspicious deaths occurred at the hospital. Tolford noted that in that time span there were 24 deaths at CHOV, compared to the usual death rate of 3 a month. According to defendant, however, the death rate at CHOV was generally much more than three per month. Defendant contends that before drafting the search warrant affidavit, Tolford knew, from information provided by coroner’s investigator Worthington, that the three-death-per-month figure was inaccurate, but that Tolford nevertheless used this figure in the affidavit, either intentionally or recklessly. At the evidence suppression hearing, coroner’s investigator Worthington testified that he arrived at the figure of three deaths per month at CHOV after examining four months of coroner’s records. But Worthington later discovered that these records were incomplete, and that records of the Riverside County Health Department showed a greater death rate at CHOV during those four months. It is unclear from the record before us when Worthington learned that the three-deaths-per-month figure was incorrect, or when he mentioned this to Tolford. Worthington testified that he “would have to guess” the date on which he checked the Department of Health’s records; his “best recollection” was that it occurred before Tolford prepared the affidavit. During Tolford’s testimony, he was not asked when he discovered that the three-deaths-per-month figure was inaccurate. Given the uncertain state of the record before us, we uphold the trial court’s finding that the affidavit’s inaccuracy with respect to the usual death rate at CHOV was not intentional or reckless. 4. Affidavit’s Statement That Defendant Attended the Patients Who Died After Exhibiting Symptoms of Lidocaine Overdose Defendant challenges as false the affidavit’s statement that he “did in fact attend every patient who died exhibiting these symptoms [seizures, acidic blood, respiratory arrest, and a bluish tint to the upper torso] in the intensive care unit.” He points out that his employment with CHOV did not start until March 29, 1981, and therefore he could not have attended any patients before that time; yet the affidavit stated that the deaths of patients exhibiting these symptoms occurred during a period of time commencing on March 8, 1981. At the evidence suppression hearing, defendant failed to establish the falsity of the affidavit’s statement quoted above. What defendant needed to show, but did not, was: (1) the identities of the patients described in the affidavit only as “every patient who died exhibiting these symptoms”; and (2) that he did not attend those patients, or that those patients did not display the symptoms described in the affidavit. The testimony presented at the hearing did not identify the patients in question. Because of defendant’s failure to establish that the challenged statement in the search warrant affidavit was false, we reject his contention that the trial court should have granted his motion to suppress the evidence seized. B. Reliability of Scientific Evidence Defendant contends that the prosecution’s scientific evidence showing that the patients died from overdoses of lidocaine was inadmissible under the “Kelly/Frye” test. (People v. Kelly (1976) 17 Cal.3d 24 [130 Cal.Rptr. 144, 549 P.2d 1240]; Frye v. United States (D.C. Cir. 1923) 293 Fed. 1013 [54 App.D.C. 46, 34 A.L.R. 145].) Under the Kelly/Frye rule, evidence based on a new scientific method of proof must satisfy three requirements before it may be admitted. First, the party offering the evidence must show that the technique is “ ‘sufficiently established to have gained general acceptance in the particular field in which it belongs.’ ” (People v. Kelly, supra, 17 Cal.3d at p. 30, quoting Frye v. United States, supra, 293 Fed. at p. 1014, italics omitted.) Second, the proponent of the evidence must establish that “the witness furnishing such testimony” is “properly qualified as an expert to give [such] an opinion . . . .” (Kelly, supra, at p. 30, italics omitted.) Third, the proponent must demonstrate that “correct scientific procedures were used in the particular case.” (Ibid.; see also People v. Ashmus (1991) 54 Cal.3d 932, 970 [2 Cal.Rptr.2d 112, 820 P.2d 214]; People v. Morris (1991) 53 Cal.3d 152, 206 [279 Cal.Rptr. 720, 807 P.2d 949]; People v. Stoll (1989) 49 Cal.3d 1136, 1155 [265 Cal.Rptr. 111, 783 P.2d 698]; People v. McDonald (1984) 37 Cal.3d 351, 372 [208 Cal.Rptr. 236, 690 P.2d 709, 46 A.L.R.4th 1011].) Defendant contends that the method used by prosecution experts to determine that the patients in this case were given large overdoses of lidocaine did not satisfy the first of these requirements. In this case, the prosecution was unable to obtain postmortem samples of the blood of 10 of the 12 deceased patients. Therefore, experts at the University of Utah’s Center for Human Toxicology used this procedure: After exhuming the patients’ corpses, the experts took samples of tissue found in various organs of the “central compartment” of the body—the lungs, brain, liver, kidney, and vitreous humor. The experts then measured the quantity of lidocaine in each of the tissue samples. From these samples, the experts extrapolated the amount of lidocaine in the organ as a whole. Based on the quantities of lidocaine in the various organs tested, the experts made a rough estimate of the amount of lidocaine in the entire body. From this estimate and the circumstances surrounding the patients’ deaths, prosecution witnesses concluded that each patient had been given a massive overdose of lidocaine shortly before death. Defendant contends that the testimony of the prosecution’s experts did not satisfy the Kelly/Frye test. Specifically, defendant argues that the trial court should have excluded the experts’ testimony that: (1) inferred amounts of lidocaine present in the patients’ bodies at death from amounts found in tissues tested long after death; (2) inferred amounts of Iidocaine in entire organs from quantities found in small samples of organs; (3) inferred, from average organ weights, the quantity of Iidocaine in the organs of decedents; (4) inferred amounts of Iidocaine in the patients’ entire body from amounts found in the patients’ “central compartment” (the internal organs from which tissue samples were taken); and (5) inferred, from amounts of Iidocaine found in the blood and tissues, that before death the patients received massive overdoses of Iidocaine. At trial, defendant never objected to any of the expert testimony on the ground that it violated the Kelly/Frye rule. Accordingly, the Attorney General argues that defendant has waived his right to argue on appeal that this testimony should not have been admitted. In response, defendant asserts four reasons why the waiver doctrine should not be applied to bar his claim. First, defendant asserts that he did object to admission of the expert testimony. He points out that he objected on the ground of “lack of foundation” when the prosecutor asked a witness to describe how Iidocaine is administered in a hospital, and objected on hearsay grounds to admission of the data obtained from the Center for Human Toxicology, arguing that the data was recorded on documents that did not satisfy the business records exception to the hearsay rule. These objections were not based on the Kelly/Frye rule, and did not seek to exclude the type of evidence to which defendant now objects. Accordingly, neither objection preserved the Kelly! Frye issue. Defendant argues that because this is a capital case, we should disregard “technical insufficiencies” in objections to the admissibility of evidence, and examine the record to determine whether there has been a “miscarriage of justice.” He relies on the lead opinion in People v. Frank (1985) 38 Cal.3d 711, 729, footnote 3 [214 Cal.Rptr. 801, 700 P.2d 415]: “On an appeal from a judgment imposing the penalty of death, a technical insufficiency in the form of an objection will be disregarded and the entire record will be examined to determine if a miscarriage of justice resulted.” The lead opinion in Frank was not signed by a majority of the court, and although later cases from this court have never disapproved its language, they have cited it only for the purpose of distinguishing it. (People v. Price (1991) 1 Cal.4th 324, 417 [3 Cal.Rptr.2d 106, 821 P.2d 610]; People v. Jennings (1991) 53 Cal.3d 334, 357 [279 Cal.Rptr. 780, 807 P.2d 1009]; People v. Carrera (1989) 49 Cal.3d 291, 324-325 [261 Cal.Rptr. 348, 777 P.2d 121]; People v. Coleman (1988) 46 Cal.3d 749, 777-778 [251 Cal.Rptr. 83, 759 P.2d 1260]; People v. Poggi (1988) 45 Cal.3d 306, 331 [246 Cal.Rptr. 886, 753 P.2d 1082]; People v. Anderson (1987) 43 Cal.3d 1104, 1129, fn. 3 [240 Cal.Rptr. 585, 742 P.2d 1306].) Moreover, here the objections in question were not merely technically insufficient, they had nothing to do with the issue complained about on appeal. Defendant also argues that even if his counsel’s objections were not explicitly based on the Kelly/Frye rule, we should consider the issue preserved for appeal because the parties understood that the purpose of counsel’s objections was to raise the Kelly/Frye issue. Defendant relies on People v. Boggess (1924) 194 Cal. 212, 232 [228 P. 448], in which we said: “While it is true ordinarily that an objection to evidence must be sufficiently specific to inform the court of the scope of the objection, nevertheless, where the record shows . . . that all the parties, including the court, must have understood the purpose of the objection, it will not be said that the objection failed of its purpose.” (See also People v. Scott (1978) 21 Cal.3d 284, 290 [145 Cal.Rptr. 876, 578 P.2d 123] [“the objection will be deemed preserved if, despite inadequate phrasing, the record shows that the court understood the issue presented”].) Here, however, the record does not show that either the prosecution or the trial court understood the objections in question to raise a Kelly/Frye challenge. Defendant’s attempt to rely on the rule set forth in Boggess thus fails. Equally misplaced is defendant’s reliance on People v. Shirley (1982) 31 Cal.3d 18 [181 Cal.Rptr. 243, 723 P.2d 1354], According to defendant, we disregarded in Shirley the failure of the defense to properly object on Kelly/Frye grounds to the use of hypnotically induced testimony. In Shirley, the defendant “moved to exclude all testimony of the . . . witness that was the result of her having been hypnotized,” arguing that “the People were attempting ‘to expand hypnosis into an area [in] which they cannot lay adequate foundation for its reliability’ as a tool for refreshing recollection.” (Id. at p. 29.) By challenging the reliability of the scientific technique in question, the defendant in Shirley properly preserved the issue for appeal. There was no similar objection in this case. In sum, defendant’s failure at trial to challenge the testimony of the prosecution experts on Kelly/Frye grounds bars him from now raising the issue. (People v. Kaurish (1990) 52 Cal.3d 648, 688 [276 Cal.Rptr. 788, 802 P.2d 278].) C. Corpus Delicti Rule According to defendant, this court’s discussion of the corpus delicti rule in People v. Ruiz (1988) 44 Cal.3d 589 [244 Cal.Rptr. 200, 749 P.2d 854] is inconsistent with the due process guarantees of the federal Constitution. As a result, he contends, the trial court in this case may have misconstrued the scope of the rule, thereby violating his right to due process. Defendant makes no showing that our decision in Ruiz, whether right or wrong, had any effect on his case, which was tried before Ruiz was decided. On that basis alone, we could probably summarily reject defendant’s claim. In any event, as shown below, the contention is without merit. In any criminal prosecution, the corpus delicti must be established by the prosecution independently from the extrajudicial statements, confessions or admissions of the defendant. [Citations.] The elements of the corpus delicti are (1) the injury, loss or harm, and (2) the criminal agency that has caused the injury, loss or harm.” (People v. Wright (1990) 52 Cal.3d 367, 403-404 [276 Cal.Rptr. 731, 802 P.2d 221].) Proof of the corpus delicti need not be beyond a reasonable doubt; a slight or prima facie showing is sufficient. (People v. Jennings, supra, 53 Cal.3d at p. 368.) In People v. Ruiz, supra, 44 Cal.3d 589, the defendant argued that, in view of the paucity of evidence of the victim’s death, the evidence was insufficient not only to support the conviction, but also to establish the corpus delicti. We disagreed, pointing out that there was ample evidence of the victim’s death by foul play, from which a reasonable inference of criminal agency could arise. In the course of our discussion, we said: “The corpus delicti ‘may be [proved] by circumstantial evidence [citation], and it need not be beyond a reasonable doubt. A slight or prima facie showing, permitting the reasonable inference that a crime was committed, is sufficient.’. . . [!]••• ‘[T]he corpus delicti rule is satisfied “by the introduction of evidence which creates a reasonable inference that death could have been caused by a criminal agency . . . even in the presence of an equally plausible noncriminal explanation of the event.’”” (Id. at pp. 610-611, quoting People v. Alcala (1984) 36 Cal.3d 604, 624-625 [205 Cal.Rptr. 775, 685 P.2d 1126], and People v. Towler (1982) 31 Cal.3d 105, 117 [181 Cal.Rptr. 391, 641 P.2d 1253], brackets in original.) Seizing on this language, defendant accuses this court of weakening the prosecutor’s burden of establishing every element of the offense beyond a reasonable doubt. He is wrong. The corpus delicti rule is a rule of law that governs the admissibility of evidence. (People v. Rogers (1943) 22 Cal.2d 787, 806 [141 P.2d 722]; 1 Witkin & Epstein, Cal. Criminal Law (2d ed. 1988) Elements of Crime, § 140, p. 156.) It has no bearing on the prosecution’s burden to prove beyond a reasonable doubt all elements of the offense; nothing that we said in People v. Ruiz, supra, 44 Cal.3d 589 alters this. There is thus no merit to defendant’s contention that our decision in Ruiz violated any federal due process requirements. D. Sufficiency of Evidence Defendant contends the evidence was insufficient to support his conviction for murdering the 12 patients. In an exhaustive analysis encompassing more than 250 pages of his 617-page opening brief, defendant argues that the evidence is insufficient to show: (1) that the patients were murdered at all; (2) assuming the patients were murdered, that defendant was the killer; or (3) assuming defendant killed the patients, that he acted with malice and with premeditation and deliberation. Although defendant has attacked the sufficiency of the evidence in general, defendant primarily focuses on the sufficiency of evidence as to each patient. Defendant’s attempt to focus on the evidence relating to each individual patient is somewhat misleading, because much of the strength of the prosecution’s case lay in the large number of patients on defendant’s shift whose deaths were accompanied by similar, highly unusual, circumstances. Symptoms that might be written off as idiosyncratic in one or two patients become highly suspicious when repeated numerous times. Accordingly, we first discuss the evidence that was common to all, or nearly all, of the 12 victims. We then address defendant’s challenges to the sufficiency of the evidence with respect to particular patients. 1. Evidence That the Patients Were Murdered As earlier stated, the theory of the prosecution was that the patients were murdered by means of massive overdoses of lidocaine. Expert witnesses testifying for the prosecution relied largely on three types of evidence to conclude that each of the twelve patients died from lidocaine poisoning: evidence of lidocaine in the tissues of the deceased patients, evidence of seizure activity, and electrocardiograph evidence. a. Lidocaine in the Tissues of the Deceased Patients Because each of the 12 patients had been gravely ill at the time of death, there initially was no suspicion of foul play. Understandably, therefore, autopsies of most of the patients were not considered necessary, and either 9 or 10 of the 12 patients were embalmed and buried. As the number of deaths at CHOV mounted, and authorities became suspicious that the patients had not died from natural causes, the bodies of the patients that had already been buried were exhumed, autopsied, and tested for lidocaine and other drugs. The bodies of patients Bayless and Boyce, who were two of the last patients to have died and had not yet been embalmed when the autopsies began, were also examined and tested. Because of the embalming, blood samples were unavailable for any of the patients except Bayless and Boyce. Accordingly, prosecution experts took tissue samples from the patients’ internal organs (heart, brain, liver, lungs, kidneys, and in some cases the vitreous humor (a watery fluid in the eyeball)), and measured the quantity of lidocaine found in these samples. Based on these calculations, the experts concluded that each of the patients had been given a massive overdose of lidocaine. Although all of the patients (with the apparent exception of patient Bayless) had been given therapeutic doses of lidocaine during their hospitalization, according to prosecution experts the amount found in the tissue samples far exceeded that attributable to the therapeutic doses. Lending additional support to the prosecution experts’ conclusion was the presence, in some patients, of relatively small quantities of MEGX, a metabolite into which lidocaine may decay, indicating that the lidocaine poisoning resulted from administration of a large overdose shortly before death, not from the buildup of lidocaine therapeutically administered over a period of time. b. Seizure Activity Witnesses observed seizures in all but two of the deceased patients, and in several other patients who did not die. These seizures (with the exception of patient Swanson’s) were extremely violent. The nurses who witnessed them had never seen such seizures in heart patients; some of the nurses likened them to epileptic seizures. The fact that the patients shared this unusual common symptom suggests that their deaths had a common cause, and that the cause was atypical. Almost all of the deaths were preceded by violent seizures, rapidly followed by cardiac and respiratory arrest. This highly unusual sequence of symptoms—seizure followed, by cardiac and respiratory arrest—had few possible causes. Although recorded cases involving massive overdoses of lidocaine are rare, prosecution experts, after reading the scanty literature on the subject, concluded that these symptoms, in the order mentioned, would be the most likely response to a massive overdose of lidocaine. Because of differences in the elimination and distribution of lidocaine from one person to the next, mild overdoses of the drug are not uncommon. But they produce symptoms substantially different from those observed in the patients in this case. Here, the patients did not exhibit the symptoms of mild lidocaine toxicity that one would expect from a slow buildup of therapeutically administered lidocaine to lethal levels. c. Electrocardiograph Evidence Each of the patients was attached to an electrocardiograph (EKG) at the time of death. The EKG produced strips of paper recording the patients’ heartbeat (rhythm strips). Some of these rhythm strips were preserved in the patients’ files. After examining the strips, the prosecution experts discovered that for most of the patients a portion of the rhythm strip showing electrical activity from the ventricles (the lower chambers of the heart), known as the QRS complex, was unusually prolonged at the time of seizures and/or cardiac arrest. Although a prolonged QRS complex may result from a variety of causes, the prosecution’s experts were of the opinion that the unusually prolonged or “broad” QRS complexes of the patients in this case were evidence that the patients were given lidocaine overdoses. Not surprisingly, experts testifying for the defense challenged the conclusions of the prosecution’s experts. Peter Ambrose, a clinical pharmacokineticist who interprets drug tests at Memorial Hospital in Long Beach and teaches at the University of California Medical Center in San Francisco, explained that in this case some of the ailments of the patients, and some of the drugs administered to them, could have substantially impaired the patients’ ability to metabolize and dispose of lidocaine. These factors, as well as the administration of cardiopulmonary resuscitation (CPR) could also have significantly affected the distribution of lidocaine in their bodies, so that instead of disbursing evenly throughout the body, the lidocaine was more likely to remain in the bloodstream and internal organs. For these reasons, pharmacokinetecist Ambrose concluded that the therapeutic dosages of lidocaine given to the patients should have caused lidocaine concentrations in their blood and internal organs that were far greater than the amounts estimated by prosecution experts. In Ambrose’s opinion, the concentrations of lidocaine found in the tissues of many of the patients were more or less consistent with the therapeutic doses administered to them. Dr. Neal Benowitz, an associate professor of medicine at the University of California at San Francisco, head of the university’s division of clinical pharmacology, and an expert in cardiovascular pharmacology, analyzed the medical records and rhythm strips of each of the deceased patients. In his opinion, each of the 12 patients could have died from natural causes, or from toxic reactions to medications therapeutically administered to them. Dr. Bramah Singh, assistant chief of the cardiology sivision at the University of California at Los Angeles (UCLA) Medical Center and professor of internal medicine at the UCLA School of Medicine, testified that the scientific data available was too inconclusive for the prosecution experts to infer that, based on the levels of lidocaine found in the tissues of the deceased patients, the patients had been given overdoses of lidocaine. Like Dr. Benowitz, he testified that each of the patients could have died from other causes. Dr. Stephen Salzman, director of cardiology and head of the coronary care and intensive care units at West Hills Hospital in the San Fernando Valley, and assistant clinical professor at the UCLA School of Medicine, testified that he had never relied on the concentration of lidocaine found in the tissues of a deceased patient as a basis from which to conclude that the patient had been given a toxic quantity of the drug. Dr. Salzman acknowledged, however, that he was not qualified to determine whether such a conclusion could indeed be reached. Based on his review of the deceased patients’ medical charts, he was of the opinion that various other causes might have led to the deaths of the patients. John Zeisler, an assistant professor of clinical pharmacy at the University of Southern California School of Pharmacy and a pharmacist at Presbyterian Intercommunity Hospital in Whittier, described two research studies he had done on the effects of lidocaine. According to him, under standard methods of lidocaine prescription a significant number of patients are given lidocaine in a dosage above the therapeutic level, and the likelihood of overdosage is particularly great with older patients. Defendant denied poisoning the 12 patients, and described at length his observations of the patients’ symptoms before their deaths. Relying on the testimony of his own expert witnesses, defendant contends that the evidence of lidocaine in the patients’ tissues does not support the prosecution’s theory that lidocaine intoxication was the cause of death. He points out that Dr. Singh testified that evidence of lidocaine in tissue samples obtained from corpses was not a reliable indicator of the amount of lidocaine administered to the patients when they were alive. In a similar vein, Dr. Salzman testified that he had never used tissue levels of lidocaine for this purpose, and knew of no doctor who had. Other defense experts, Dr. Benowitz and pharmacokineticist Ambrose, while accepting the viability of using tissue samples to determine quantities of lidocaine administered before death, concluded that the quantities found in the deceased patients were consistent with the amounts therapeutically administered to them while they were alive. The significance of the lidocaine concentrations found in the patients’ tissues was hotly contested at trial. This dispute, however, was properly one for the trier of fact, not the reviewing court, to resolve. As a reviewing court, our role is limited to determining whether there is substantial evidence to support the decision of the trier of fact. Substantial evidence is defined as “evidence which is reasonable, credible, and of solid value— such that a reasonable trier of fact could find the defendant guilty beyond a reasonable doubt.” (People v. Johnson (1980) 26 Cal.3d 557, 578 [162 Cal.Rptr. 431, 606 P.2d 738, 16 A.L.R.4th 1255].) In this case, the prosecution presented testimony by a number of highly qualified expert witnesses, who concluded from the lidocaine concentrations in the patients’ tissue samples that the patients had been given massive overdoses of lidocaine. The trier of fact could reasonably credit this testimony. Defendant also argues that the prosecution experts improperly relied on the patients’ broad QRS complexes as a factor indicative of lidocaine overdose. Defendant asserts that there are a number of possible causes of broad QRS complexes. But although the possibility of other causes may reduce the weight to be attached to the evidence that the patients had broad QRS complexes, this evidence was one link in the circumstantial chain of evidence that the patients died from overdoses of lidocaine, and was properly relied upon by the prosecution experts. Defendant minimizes the significance of the seizures suffered by the patients, asserting that in most cases the percipient witnesses disagreed as to whether the seizures occurred. This assertion is true only if defendant is included as one of the percipient witnesses. Except for defendant’s testimony, there was no dispute that most of the seizures occurred, although in some cases witnesses who had arrived in the ICU after the seizures had begun testified that they could not remember whether they had seen seizures. The trial court could reasonably believe the ICU nurses who offered credible, convincing testimony that the seizures occurred. Finally, defendant contends that the patients’ medical records, relied on by the experts for the prosecution (and, we note, the experts for the defense), were too unreliable to satisfy the business records exception to the hearsay rule (Evid. Code, § 1271), and that the trial court should have sustained defendant’s objection to their introduction. Because this contention is raised as part of defendant’s claim that the evidence was insufficient to support the verdict, we address it here. To satisfy the business records exception to the hearsay rule, the proponent of the evidence must show, among other things, that “[t]he sources of information and method and time of preparation were such as to indicate its trustworthiness.” (Evid. Code, § 1271, subd. (d).) According to defendant, the medical records in this case were untrustworthy, inaccurate, and incomplete. He cites testimony by the custodian of the records that items were missing from most of the files, and that the nurses sometimes did not complete the patients’ charts until the end of their shifts, hours after the events recorded actually occurred. Defendant also points to evidence that at times nurses gave patients medications but neglected to record that fact in the patients’ charts. Although there were undoubtedly deficiencies in the patients’ medical records (Nurse MacDonald testified that CHOV had a “chronic problem” with incomplete charts), these deficiencies were not so great as to require the trial court to exclude the records from evidence. Jean McCormick, CHOV’s administrator, testified that the fact that certain items were missing from the files did not impair the accuracy of those items that were remaining; the defense offered no testimony to impeach her. Furthermore, the trial court, as trier of fact, was aware of the deficiencies in the records, and could discount their weight accordingly. It is well established that, as a general rule, “hospital records are business records and as such are admissible if properly authenticated.” (People v. Moore (1970) 5 Cal.App.3d 486, 492-493 [85 Cal.Rptr. 194].) In this case, the records were properly authenticated, and the trial court could reasonably conclude that the method of preparing them was sufficiently reliable to justify their admission. For the reasons set forth above, we conclude there is substantial evidence to support the trial court’s conclusion that someone had administered large overdoses of lidocaine to the patients, causing their deaths. 2. Evidence That Defendant Was the Killer If we make the not-unreasonable assumption that all fatal overdoses were administered by the same person, defendant must be the killer. The patients were poisoned at night, in the hospital’s ICU, where the presence of a stranger certainly would have attracted the staff’s attention. At least two nurses were on duty on each of the nights when overdoses were administered, but defendant was the only nurse who was on duty on all of those nights. None of the other nurses was present on any more than five of the relevant nights. Although no one saw defendant inject the fatal overdoses, in each of the 12 instances he had the opportunity to do so, and many of the victims started having seizures soon after defendant announced that he was about to give them medication. Moreover, as we shall discuss below, other circumstantial evidence suggested that defendant was injecting patients with superconcentrated lidocaine: the “Neble bolus,” the “Boyce bolus,” evidence that defendant kept lidocaine in his pockets, and lidocaine found in defendant’s home. a. The Neble Bolus (Preloaded Syringe Found by Neble) On April 24, 1981, one day after the death of the eleventh of the victims in this case, CHOV closed its ICU, which was never to reopen. Seven months later, a construction worker named Michael Neble was tearing down drywall in the ICU when he saw a bolus or preloaded syringe (the “Neble bolus”) sticking out of one of the beds. The label on the bolus indicated a 2 percent solution of lidocaine, but expert analysis established that the bolus contained a 23 percent solution of lidocaine. Nurse MacDonald’s fingerprint was found on the bolus. According to the prosecution, defendant had asked Nurse MacDonald to inject the contents of this bolus into patient Castro on the morning of April 20, 1981. The prosecutor theorized that, knowing MacDonald’s print was on the bolus and attempting to deflect suspicion onto MacDonald, defendant “planted” the bolus in the bed. b. The Boyce Boluses Shortly before patient Boyce’s death on April 23,1981, CHOV, which was concerned about the high death rate in its ICU, adopted a policy that all syringes used to inject patients with medication were to be placed in a box. Among those syringes collected were two boluses (preloaded syringes) labeled “Boyce, Bertha, 4-22-81,” in defendant’s handwriting. Each was nearly empty. According to the labels, one bolus should have contained a 2 percent solution of lidocaine while the other should have had a 1 percent solution. Expert analysis of the liquid remaining in the boluses established that one had 22.6 percent lidocaine and the other 20.9 percent lidocaine. c. Lidocaine and Syringes Observed in Defendant’s Pockets Nurse Cheville testified that every night while on duty with him, she saw defendant carry a box of lidocaine in his shirt pocket. When she asked him why, defendant replied that he wanted the lidocaine available in case it was needed. On the morning of patient Silvera’s death, Nurse Race saw a glass syringe and several plastic syringes in defendant’s pocket; on another occasion she saw defendant take a vial of medicine from his pocket and draw the medicine into a plastic syringe. In shape and size, the vial resembled a two-gram vial of lidocaine. d. Evidence Found at Defendant’s House Acting under a warrant to search defendant’s house, the police retrieved a garbage bag containing a brown paper bag that had a half-empty two-gram vial of 20 percent lidocaine. Also in the garbage bag were several syringes and an empty box designed to hold a 1 percent vial of lidocaine. In a closet in the master bedroom, the police found a box containing a sealed vial of 1 percent lidocaine. Notwithstanding the mass of circumstantial evidence linking defendant to the murders of the 12 patients, defendant maintains that the evidence was insufficient. He contends that being on duty the night each of the patients died merely places him at the scene of the crime. He argues that “[m]ore is needed” because the scene of the crime was “a busy hospital, open to the public and staffed by a wide variety of people.” But the patients’ seizures occurred in the middle of the night, when a “wide variety of people” was not present. Also, the seizures took place in the hospital’s ICU, where, because of the patients’ fragile condition, visitors are generally limited to the patients’ close relatives. Defendant also attempts to minimize the significance of the lidocaine found in his home, claiming it was “no more than the ordinary medical debris a registered nurse might accumulate.” Certainly, the presence of lidocaine in defendant’s house, when considered in isolation, cannot be likened to a “smoking gun”; it was, however, a link in the circumstantial chain of evidence identifying defendant as the person who administered overdoses of lidocaine to the 12 patients. Considered in its entirety, the evidence pointed unerringly to defendant as the killer. 3. Evidence of Malice and of Premeditation and Deliberation Next, defendant argues that even if the evidence established him to be the killer of the 12 patients, it does not show that he acted with malice, an element of the crime of murder. (§ 187.) He points out that both prosecution and defense experts testified regarding instances of accidental lidocaine overdoses in other hospitals, and he theorizes that perhaps this was the case here. The contention borders on the frivolous. Defendant’s own testimony establishes that he was a trained nurse and well aware of lidocaine’s effects and proper dosages. Although conceivably defendant could have given an unintentional overdose of lidocaine to a single patient, it is inconceivable that defendant accidentally gave fatal overdoses of lidocaine to 12 patients in the short time span of 4 weeks. Defendant also contends the evidence was insufficient to show premeditation and deliberation, and therefore the murders were not shown to be of the first degree. Not so. The manner in which the 12 murders were committed shows that they could not have been spontaneous acts. More important, when a murder is accomplished by means of poison, additional proof of premeditation and deliberation is not required to establish it as first degree murder. (§ 189; 1 Witkin & Epstein, Cal. Criminal Law, supra, Crimes Against the Person, § 467, p. 527; see People v. Ruiz, supra, 44 Cal.3d 589, 614 [lying in wait]; People v. Wiley (1976) 18 Cal.3d 162, 168 [133 Cal.Rptr. 135, 554 P.2d 881], [murder by torture].) Because defendant murdered the 12 victims by poisoning them with lidocaine overdoses, the murders were necessarily of the first degree. 4. Evidence Pertaining to Each of the Individual Patients In addition to his claim, addressed above, that the evidence as a whole is insufficient to support the convictions, defendant also makes specific attacks on the sufficiency of the evidence that he killed each of the 12 patients. We reject the challenge. Before discussing the facts of each killing, we summarize the procedures employed at CHOV’s ICU, where 11 of the 12 victims died. The ICU at CHOV contained six beds, but during most of the period relevant here was not fully occupied. Each bed was in a separate room with a large window to enable nurses to look in. During the night shift, between two and four nurses worked in the ICU, depending on the number of patients. Although no doctors worked in the ICU, one was always on duty in some other part of the hospital, and was thus available to render assistance in a life-threatening emergency, in hospital parlance a “code” or “code blue.” As is customary in ICU’s, the registered nurses (RN’s) were given substantial authority to administer medication to the patients if the symptoms they observed warranted it. This was done through the use of “standing orders,” which authorize the nursing staff of an ICU, when a doctor is not available, to administer prescribed dosages of specified medications when the patient exhibits certain described symptoms. CHOV’s standing orders permitted RN’s to administer lidocaine to patients when they observed specified cardiac irregularities. Patients were commonly given lidocaine in a two-step process: an initial injection of between 50 and 100 milligrams of lidocaine, followed by an intravenous (IV) drip. The initial injection was administered from a preloaded syringe, known as a bolus, containing a 2 percent solution of lidocaine. The IV drip or “infusion” was prepared by adding a vial of 20 percent lidocaine to a bottle of bulk fluid, which was then attached to a needle that had been inserted into a vein, and allowed to drip slowly into the patient’s bloodstream at a rate of between one and four milligrams per minute. In theory, the amount of lidocaine infused would equal the amount eliminated by the body, and a constant, therapeutic level of lidocaine would be maintained in the bloodstream. In this case, the prosecution theorized that defendant removed the 2 percent solution from boluses of lidocaine and replaced it with a 20 percent solution from the vials, and that defendant then administered this solution to the victims. As a result, the victims received 1,000 milligrams or more of lidocaine in a matter of minutes. According to prosecution experts, an injection of 1,000 milligrams was likely to be lethal. For a patient receiving a therapeutic lidocaine infusion, an additional injection of as little as 500 milligrams of lidocaine was potentially fatal. To facilitate the rapid administration of medications, each patient was hooked to at least one and sometimes two IV lines, which normally flowed into veins in the patient’s arm. When no medication was being administered, the bottles attached to the lines contained a solution of dextrose and water. To monitor their heartbeats, most of the patients were connected to EKG’s. Although each nurse took primary responsibility for one or more patients in the ICU, the nurses functioned as a team; thus, it was not uncommon for a nurse to enter the room of another nurse’s patient to check, assist, or give medication to the patient. We now discuss, in chronological order, the facts surrounding the death of each of the 12 patients who died in the hospital’s ICU while defendant was attending them as a nurse. a. March 29, 1981: Death of Irene Graham At 11:00 p.m. on March 29, 1981, three nurses began working the night shift in CHOV’s ICU: Dorothetta Ernest, Donna MacDonald, and defendant. The care of eighty-nine-year-old Irene Graham, one of six patients in the unit, was entrusted to Nurse Ernest. Graham had been admitted to the ICU earlier that evening for chest pains following a burglary at her home. She also suffered from congestive heart failure, a condition in which the heart is unable to pump efficiently, causing blood to build up in the lungs and other organs. EKG rhythm strips indicated that she had an ongoing myocardial infarction (heart attack). According to Nurse Ernest, for the first five hours after Graham’s admission her vital signs were stable and her heartbeat was regular, with occasional premature ventricular contractions. While Ernest was on a lunch break between 4:30 and 5:00 a.m., defendant told Nurse MacDonald that Graham was having problems, and requested that she ask Nurse Ernest to return. When Ernest returned, Graham was sleeping, and defendant was injecting something into Graham’s IV line. Defendant told Nurse Ernest that Graham had been experiencing ventricular tachycardia (a rapid heart beat arising from the heart ventricles), and that he was therefore giving her two boluses of lidocaine. (If these were indeed Graham’s symptoms, the treatment was appropriate under the hospital’s standing orders.) Nurse Ernest called Graham’s doctor to report Graham’s ventricular tachycardia; the doctor ordered a lidocaine drip, which was commenced at 5:30 a.m. Fifteen minutes later, while Nurse Ernest was making entries in charts, patient Graham suddenly screamed and had a massive seizure, which Ernest described as similar to a grand mal epileptic seizure but more violent. Shortly thereafter, Graham stopped breathing, which was rapidly followed by cardiac arrest. Resuscitative efforts were unsuccessful, and Graham was pronounced dead at 6:15 a.m. Defendant maintains that Graham died from natural causes. He points out that Graham was 89 years ol