A co-author of a controversial research paper on stem cells, Yoshiki Sasai, was found dead this morning.

Sasai was a scientist with the government affiliated research institute Riken.

According to sources, Sasai was found hanged by a security guard inside the medical center building next to the research institute in Kobe.

He was rushed to the hospital but was confirmed dead.

An apparent suicide note was also found.

Sasai was a supervisor of Haruko Obokata, a co-author of a controversial research paper on stem cells.

The research had to be retracted because of its falsified content.

During a news conference held by Riken, a spokesperson said Obokata was deeply shocked.