TOKYO - A renowned Japanese stem cell scientist who co-wrote research that was later retracted in an embarrassing scandal has been found dead of an apparent suicide, police said Tuesday.
The body of Yoshiki Sasai, 52, was discovered hanging inside the stairwell of a building that houses the Riken Centre for Developmental Biology, one of the country's most prestigious scientific research institutions.
The office is in the western city of Kobe.
"Yoshiki Sasai was discovered hanging on Tuesday morning inside one of Riken's research buildings and, after being sent to hospital, he was confirmed dead at 11:03 am," a spokesman for the Hyogo Prefectural police told AFP.
"Police are investigating the case as a suspected suicide."
He added that authorities discovered "farewell notes" that Sasai had left behind, with public broadcaster NHK reporting that one was left for Haruko Obokata.
Sasai mentored the 30-year-old Obokata, whose study earlier this year was hailed as a "game-changer" in the quest to grow transplant tissue in the lab.
But the feted research unravelled amid claims Obokata used fabricated data in her research.
Leading science journal Nature said last month it had withdrawn the study after mistakes were discovered in some data published in two papers, among other problems.
In the aftermath of the scandal, Sasai was accused of failing to properly supervise Obokata. He later apologised.
"It's extremely regrettable," Japan's top government spokesman and Chief Cabinet Secretary Yoshihide Suga told reporters in response to questions about Sasai's death.
"Dr Sasai was a leading contributor in the field of regenerative medicine."