Yoshiki Sasai, a prominent Japanese researcher, hanged himself to death at his research institute in Kobe.

Sasai held the position of Deputy Director at the RIKEN Center for Developmental Biology. His name was involved in two research studies that were withdrawn from journal Nature. He was one of the co-authors of two papers that suggested a quick way of coming up with versatile stem cells.

Researchers in the papers suggested that they have come up with flexible cells by bathing them in acid for 30 minutes and spinning them in a centrifuge for five minutes. Researchers were happy with the creation called as stimulus-triggered acquisition of pluripotency (STAP).

But after a few days, questions were raised on the credibility of the papers and methods conducted by researchers for the study. The questions led RIKEN to conduct an investigation into the matter and many scientific problems were found on the part of study leader Haruko Obokata. Questions were also raised on co-authors of the study as to how they could have allowed the submission of the study without checking its credibility.

Both studies were withdrawn in July. RIKEN blamed Sasai for not checking the data used in the study. Sasai took the criticism to heart. "As a researcher, I am deeply ashamed of the fact that two papers of which I was an author were found to contain multiple errors and, as a result, had to be retracted", said Sasai during the time when researches were retracted.

Sasai has left five suicide notes. RIKEN President Ryoji Noyori said in a statement that the scientific world has lost a talented and dedicated researcher. He had earned a lot of respect for advanced research that he carried out over many years.