This in turn hampered the investigation, as there were no easily discernible correlations between changes in the distribution or rate of deaths and his shift pattern (a commonly used tool in examining whether malpractice is taking place).
In searching for evidence that would be strong enough to obtain a conviction, police exhumed the remains of patients who had died while Saldivar had been on duty and been buried (rather than cremated).
The marker that was being sought was unusually high levels of Pavulon in the cadaver, as this drug remains identifiable for many months (unlike succinylcholine chloride and morphine which are decomposed into innocuous compounds relatively quickly).
On March 12, 2002, at age 32, Saldivar pleaded guilty to six counts of murder and received seven consecutive life sentences without the possibility of parole.
Statistical analysis indicates that the total number of murders committed by Saldivar could be as high as 200,[citation needed] but no convincing physical evidence will ever be available to confirm or refute this possibility due to bodies being cremated after death or simply the effects of bodily harm.