The nurse may have killed dozens of poisoned drops

REUTERS / Paulo Whitaker [19659002] The nurses worked in pairs, Asahi Shimbun reported, and Kuboki administered the deadly chemicals while his colleagues were busy briefing as the teams changed. Forty-eight deaths occurred between July and September 2016, including five on a single day in August and four on a day in September, according to the Japan Times . The newspaper quoted Kuboki's mother, who said her daughter was afraid to work at the hospital at night and wanted to quit her job.

Investigators began investigating suspicious deaths after traces of chemical benzalkonium chloride were used in disinfectants. discovered in the bodies of Nishikawa and Yamaki. The police concentrated on Kuboki after analyzing the uniforms of the hospital workers, noting that only his were carrying traces of the chemical.

Hospital staff found at least 10 unused infusion bags. At first, Kuboki denied any involvement, even expressing sympathy for the families of the dead and saying that she had not noticed anything suspicious at the hospital.

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Kuboki started working at the hospital in 2015. She reportedly told the police that she was only targeting critically ill patients, although hospital records dispute this. Since many bodies were cremated before the tests could be performed, Kuboki may have killed many more people than she admits.

Former colleagues told Asahi Shimbun that they had no idea Kuboki of the dead. "We had no idea that she was a problem employee," one of the journalists told the newspaper. Another, who worked alongside Kuboki at another hospital, said she was "considered competent", although she was "the kind of person hard to understand".