The suicide of Yoshiki Sasai, a globally renowned researcher and co-author of controversial stem cell research, could have been avoided if the Riken research institute had implemented reform measures proposed in June and had accepted his resignation earlier in the year, the former head of an independent panel said Wednesday.

“If Sasai was able to quit Riken when he offered his resignation as deputy director in March, there would possibly be no trouble” now, said Teruo Kishi, who chaired the reform panel that proposed the measures for the institute, including the Riken Center for Developmental Biology in Kobe.

“And if Riken had replaced Sasai in accordance with our proposal (which called for all executives at the Kobe facility, including Sasai, to be replaced), this wouldn’t have happened,” Kishi said in a telephone interview with The Japan Times, lamenting the loss of Sasai, who he described as “a gem.”

Sasai, 52, was found Tuesday hanging from a stairway handrail in a building at Riken’s Kobe facility.

Kishi said verification of the existence of so-called STAP cells will become more difficult with Sasai’s death. The existence of these versatile stem cells, claimed by Sasai and researcher Haruko Obokata, has been the center of a major controversy and charges of misconduct. Researchers are now attempting to duplicate the results of their experiments.

“It will be a huge blow (to reproducing STAP cells) with the loss of one of the two key figures,” Kishi said.

Obokata claimed she had succeeded in creating STAP cells, while Sasai stressed that some data in the research were hard to explain in the absence of the phenomenon.

As the supervisor of Obokata’s writing, Sasai was co-author and corresponding author of the two controversial STAP papers that were published in the prestigious British science journal Nature in January and then retracted in July.

The reform panel led by Kishi, set up to explore ways to prevent further research misconduct at Riken, called on Riken President Ryoji Noyori to slap severe penalties on Obokata and Sasai, and dismantle the Kobe biology center in its present form.

Masatoshi Takeichi, director of the center, reportedly said Tuesday that Sasai’s death wouldn’t affect the course of the STAP verification process, which is being led by Riken researcher Hitoshi Niwa. Sasai was not involved.

However, Kishi, president of the Innovative Structural Materials Association in Tokyo, stressed that Sasai’s death will have a psychological impact on the people trying to reproduce STAP cells.

“There was no way Obokata wasn’t shocked. Niwa also will run out of steam,” Kishi said, adding that Riken must be mindful of the emotional strain caused by Sasai’s death.

Riken is scheduled to compile an interim report on the work headed by Niwa by the end of this month. The verification experiments, which commenced in April, are expected to last about a year.

After doubts were raised about the STAP research, a Riken investigative committee said in late March that it found two instances of research misconduct by Obokata. Then the institute announced in late June that it had started a preliminary investigation into possible further misconduct after new questions emerged.

Riken also said at that time Obokta would take part in a separate experiment to verify her findings, scheduled to run until Nov. 30.