As Ontarians grapple with one of Canada’s worst alleged serial killings, Japanese authorities are investigating their own string of suspicious elderly deaths — involving as many as 48 victims and a culprit still at large.

A month before Elizabeth Wettlaufer was charged in the deaths of eight nursing home residents in Ontario, a police investigation was triggered in Japan after two 88-year-old patients died at a hospital in Yokohama, the country’s second-largest city.

According to news reports, an autopsy found that a patient named Sozo Nishikawa had been fatally poisoned by a hospital disinfectant on Sept. 18. Two days after his death, a second male patient from his hospital room, Nobuo Yamaki, died after his heart rate dropped and triggered an alarm.

Both patients died shortly after their drip bags were replaced. Police suspect the deaths could be the work of a mercy killer, or a so-called “angel of death.”

Police searched 50 unused IV bags at the hospital, local media reported, and ten had small holes pierced into the rubber seal connecting the IV bag and tube. The bags were all stored in the nurses’ station.

There could also be more victims — many more. According to reports, 46 other patients also died between July and September, all from the same hospital floor.

Workers at the 85-bed facility initially attributed the sudden spike in deaths to the fact that the hospital had recently been accepting more seriously ill patients, the Japan Times reported last month.

“We see many people pass away due to the nature of this hospital but had the impression that the number of those dying was increasing a bit,” a hospital official told the newspaper.

However, the two poisoning deaths follow a string of disturbing incidents at the hospital this summer, including a nurse whose apron was slashed and an employee whose lips were blistered after drinking a beverage laced with bleach.

According to a recent Japan Today editorial — which calls for more security and oversight of health-care facilities — local government authorities were notified of the disturbing incidents over the summer and urged hospital officials to notify police. This advice was reportedly ignored because the hospital wanted to resolve its problems internally.

Police have yet to announce a suspect but its believed the killer could have medical expertise or connections to the hospital. A source told Japan Today that “it’s difficult to imagine a situation that an outsider entered the nurse station and tampered (with the drip bags).”

Japan has experienced a number of other attacks at health facilities in recent years, all in the same Kanagawa prefecture as the two poisoning deaths.

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In July, Satoshi Uematsu, a former nursing care attendant, stabbed and killed 19 residents at a facility for mentally handicapped people in the city of Sagamihara. He also injured 27 other patients and staff and told police he euthanized the patients “for the benefit of society.”

In 2014, an ex-employee of a nursing care facility in Kawasaki city was also charged after he allegedly admitted to throwing three elderly residents off their balconies.

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