Eric Lander, President Biden’s top science adviser, resigned on Monday night after it was reported that an internal White House investigation found that he had bullied his former general counsel.

Lander was director of the Office of Science and Technology Policy, a Cabinet-level position. In his letter to Biden, Lander said it “has been a great honor” to serve as science adviser, and he is “devastated that I caused hurt to past and present colleagues by the way in which I have spoken to them. But it is clear that things I said, and the way I said them, crossed the line at times into being disrespectful and demeaning, to both men and women.”

Politico was the first to report on the investigation into Lander, which found there was “credible evidence” he bullied then-general counsel Rachel Wallace and had “disrespectful interactions with staff.” More than a dozen current and former Office of Science and Technology Policy staffers also spoke with Politico, and said Lander belittled, cut off, and dismissed subordinates and talked to women “in a demeaning or abrasive way in front of other staff.”

On Monday afternoon, White House Press Secretary Jen Psaki said Biden has been “crystal clear with all of us about his high expectations of how he and his staff should be creating a respectful work environment,” and changes would be made at the Office of Science and Technology Policy.

Lander is the first Cabinet-level member of the Biden administration to resign. A professor at MIT and Harvard Medical School, he was the founding director of the Broad Institute, a MacArthur Fellow, and a leader of the Human Genome Project.