GRAND RAPIDS, Mich. (WOOD) — A professor has left the University of Michigan after an investigation into his past work found “research misconduct” and led the university to reach out to multiple medical journals to retract the implicated studies.

Spokesperson Kim Broekhuizen confirmed to News 8 that Dr. Chung Owyang, a gastroenterology researcher with Michigan Medicine, was no longer with the university as of Jan. 2.

According to nonprofit group “Stop Animal Exploitation Now!” an internal investigation by the university found that Owyang worked on four studies that included falsified or fabricated data. Those studies used more than $5 million in federal grants.

According to the National Library of Medicine, the four impacted studies were published between 2004 and 2012. Overall, the four studies were cited by 75 other research projects.

“The University of Michigan is committed to fostering and upholding the highest ethical standards in the conduct of research and scholarship,” Broekhuizen said in a statement. “U-M’s Office of the Vice President for Research employs a Research Integrity Officer responsible for addressing and assessing allegations of research misconduct. All allegations of research misconduct are thoroughly reviewed for appropriate next steps.”

SAEN has called for a “full investigation of these University of Michigan publications and all associated authors.”

“It is even worse that hundreds of rats were subjected to highly invasive procedures and killed for fraudulent experiments. This project took the lives of animals to produce data that was, according to the University of Michigan itself, falsified,” SAEN Executive Director Michael Budkie said in a letter to the U.S. Department of Health and Human Services’ Office of Research Integrity. “At the end of the investigation I am certain that the events surrounding these retractions will be judged to constitute research misconduct. A multi-year pattern of fabricated/falsified data involving many of the same staff in multiple publications would appear to be intentional.”

Of the four publications in question, one co-author has worked on all four studies, while another worked on three of the four and another worked on two of the four.

Broekhuizen would not comment on whether any other researchers would face any punishment, citing university policy to not discuss personnel matters.

CORRECTION: A previous version of the story reported Owyang was fired. A university spokesperson now says the professor left on his own terms. We regret the error.