TOKYO (AP) — Police say a senior Japanese scientist embroiled in a stem-cell research scandal has apparently committed suicide.

Yoshiki Sasai had supervised and co-authored stem-cell research papers that had to be retracted due to falsified contents.

Police say Sasai, 52, was found Tuesday at a government science institute RIKEN in Kobe, western Japan.

RIKEN said a security guard found him suffering from cardiac arrest, with a rope around his neck. Sasai was rushed to a hospital but was pronounced dead two hours later.

Police said Sasai left what appeared to be suicide notes, but refused to disclose their contents.

Sasai’s team retracted the research papers from British science journal Nature over co-author Haruko Obokata’s alleged malpractice, which she has contested.

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