One of the Uruguayan nurses who confessed to killing 16 patients did so to halt their suffering, his defense lawyer said, accusing the other of having acted out of disgust at their infirmities. The nurses had treated patients for more than a decade, raising fears the final death toll could rise and leading countless families to wonder whether their relatives had died from natural deaths or been murdered by their caregivers. Ines Massiotti, the defense attorney for Ariel Acevedo, 46, said late Tuesday that her client, who was jailed Sunday after confessing to killing 11 patients, had said that he killed them "so they would not have to suffer more." "Ines, I have worked in the ICU for 20 years and have seen thousands of people die. What happened to me? I don't know. I think I believed in God," she quoted him as saying, during her interview with El Espectador radio. "Now I realize I was wrong and that I acted as though I was God... I'm sorry," he said, according to Massiotti. But Massiotti said Marcelo Pereira, the other nurse, who is accused of killing five people at the hospital, was "evil." Officials said earlier on Tuesday that the two male nurses took advantage of emergencies to steal drugs that they then used to commit murder. But neither police nor health officials would officially comment on the final number of murder victims. Deputy Health Minister Lionel Briozzo said at a press conference that hospitals and clinics normally keep records and control how medications are used for each patient. But "when emergency cases intervene -- fairly common in intensive care centers -- such as cardiac arrest or massive bleeding, immediate resuscitation measures are started (and) control is set aside to address the importance of giving immediate medication to save a life," he said. The system for safeguarding medication did not fail, Briozzo said, but there were "persons who, instead of reviving people, were speculating about how to steal drugs to keep them and then kill other people." Police arrested the two nurses on Sunday and charged them with murdering patients at a private Neurological Intensive Care Center and at a public hospital's intermediate-level care unit. The health ministry on Tuesday opened a probe of hospital management with help from experts with the Pan American Health Organization (PAHO). "Nobody could anticipate from the health point of view a criminal epidemic," said Eduardo Levcovitz, PAHO's representative in Uruguay. Health officials said they are looking into installing cameras at some hospital sites to monitor patient care, to be used only in cases of emergency like an airplane's "black box." Miriam Rodriguez, the daughter of Santa Gladys Lemos -- a 74 year-old diabetic woman who was about to be released but died after one of the nurses treated her -- said there could be many more victims. Rodriguez told AFP she got a call Sunday from a judge, who told her that her mother's death had not been natural. "The judge told us that there were lots of people, scores, scores of deaths," she said, adding that she was "disgusted" by what she says is a cover-up by hospital workers. Health Minister Jorge Venegas on Monday described the suspects as "serial killers," and promised far-reaching inspections of both private and public medical facilities.