Mayo Clinic is shutting down a prominent lab working on federally funded research led by well-known anti-aging and cancer researcher, who is accused of bullying and “petulant toddler” behavior.

There have been many anonymous accusations made to the Post Bulletin about Dr. Jan van Deursen screaming, threatening, intimidating and generally mistreating the students and staff who work in his lab.

Robin Ricke, a former postdoctoral fellow worked in the lab from 2007 to 2014, is the first to publish a signed statement alleging that bullying and “petulant toddler” behavior by van Deursen created a “pressure cooker” environment and may have prompted Mayo Clinic's closure of the lab.

The lab is supported by millions of dollars in grants from the National Institutes of Health to study how age-related diseases and disorders are affected by aging cells and how eliminating senescent cells might improve and extend the human life span. Van Deursen spun that research into Unity Biotechnology, a San Francisco-based biotechnology firm he co-founded that attracted big investors, including Amazon's Jeff Bezos, the world’s richest man.

Mayo Clinic has declined to say if van Deursen is still an employee or if rumors that he retired earlier this year are correct. Sources inside the lab say he "retired" in December following charges of misbehavior. However, while he has not physically been in the lab since then, the staff is required to continue to report to him as he directs the lab remotely.

“Mayo Clinic is in the process of responsibly concluding the research activities associated with Dr. van Deursen’s laboratory, including the important work of our students and employees. By policy we do not discuss publicly personnel matters,” Robert Nellis, of the Mayo Clinic Department of Public Affairs, wrote last week. "Mayo Clinic is committed to providing a safe work and learning environment that is free of harassment, bullying, discrimination, and disrespectful behavior.... Mayo Clinic’s commitment to safety also includes meeting applicable reporting obligations with governmental and regulatory agencies, including the National Institutes of Health.”

Van Deursen worked at Mayo Clinic for more than 20 years, where he has served in many leadership roles including the chairman of biochemistry and molecular biology at Mayo Clinic. He is the director of the Robert and Arlene Kogod Center on Aging's senescence program at Mayo Clinic. Van Deursen has been awarded many honors at Mayo Clinic, such as Distinguished Investigator, Investigator of the Year and Distinguished Lecturer.

Efforts were made to reach van Deursen directly by social media and through Mayo Clinic, as well as through Unity Biotechnology. He could not be reached.

While Mayo Clinic is not publicly discussing the turmoil involving van Deusen’s research lab, it is a hot topic on an independent news blog based in Germany called “For Better Science.” Journalist Leonid Schneider wrote a post based on multiple anonymous sources in June stating that van Deursen, facing allegations of bullying, retired from Mayo Clinic in January.

On Friday, Schneider followed that up with a first-person account by Ricke. Van Deusen lists Ricke on his curriculum vitae among the scientists whom he has mentored.

Ricke described being notified that van Deursen had been “pushed out,” after being placed on administrative leave for a month. That didn’t surprise Ricke, who said van Deursen refused to speak to her as she concluded her employment at the lab. She described it as “behavior reminiscent of a petulant toddler.”

“Based on my interactions with Jan, the surprising part was that Mayo Clinic administration finally reacted to the bullying complaints. I personally witnessed his bullying behavior and was a target,” Ricke wrote. “There is a clear difference between being a taskmaster and a bully. There just is. Jan was definitely both.”

She described him as regularly yelling at staff, with a focus on non-English-speaking immigrants, who depended on their jobs to remain in the U.S. Ricke added that he also intimidated staff to work long hours, even when ill or during bad weather.

"An example of an inappropriate joke that Jan told multiple times was that he wanted to treat poorly performing students or postdocs like how Kim Jong Un had treated his uncle, by feeding his uncle to wild dogs," she wrote.

While several workers in van Deursen’s lab have commented on the blog and even reached out to the Post Bulletin, most refused to identify themselves for fear of losing their jobs or harming their career prospects. Ricke, who has left the medical research field, said such issues don’t hinder her. After all these years, she said, van Deursen’s behavior still bothers her.

“I know people left the lab in unfortunate circumstances both before and after me. I feel like my silence makes me somewhat culpable. How many destroyed careers are in Jan’s wake? Future trainees in Jan’s lab should know exactly what kind of mentorship they are signing up for," Ricke wrote.

"Second, Mayo Clinic has finally reacted. That in combination with the NIH policy on a hostile work environment means that Jan’s bad behavior should have some professional consequences in addition to bad karma,” she continued.

Unity Biotechnology, co-founded by van Deursen in 2011, has succeeded in attracting a lot of attention and money. In 2016, United landed a jaw-dropping $116 million in Series B financing from investors that included Bezos.

Jason Spark of Unity Biotechnology did confirm that “Dr. van Deursen is a scientific co-founder of Unity, however he is not an employee of Unity."