Dr. Eric Lander, President Biden's top science adviser, resigned on Monday after an internal probe discovered convincing evidence that he mistreated and demeaned his colleagues.

Lander's departure from the Office of Science and Technology Policy occurred after The White House suggested that he would retain his position earlier in the day. This decision contradicted Biden's day-one pledge to terminate any officials who mistreat their colleagues.

"The President accepted Dr. Eric Lander's resignation letter this evening, expressing gratitude for his work at OSTP on the pandemic, the Cancer Moonshot, climate change, and other critical priorities," White House press secretary Jen Psaki said late Monday.

"He is confident that Dr. Lander will continue to make significant contributions to science in the years to come."

According to Politico, the probe into Lander was sparked last year by a workplace complaint lodged by his then-general counsel, Rachel Wallace.

The assessment concluded that Lander was rude to staff members and violated the department's "Safe and Respectful Workplace Policy."

The site got recordings and documentation relating to the investigation, which revealed that Lander had bullied several female staff members in addition to Wallace.

Of the office's approximately 140 employees, 14 current and former employees stated that they worked in a hazardous atmosphere under Lander. Nine employees asserted that Lander would yell at and humiliate them in front of their peers.

The assessment found no indication of gender discrimination, and the White House determined that the reassignment of the staffer who made the first complaint last year was "appropriate."

Lander expressed regret for his behavior in his resignation letter.

"I am devastated that the way I have spoken to former and current colleagues has caused them pain," Lander added.

"I believe it is impossible for me to continue in my current capacity effectively, and the work of this office is far too critical to be harmed," he continued.

Lander's resignation represents the Biden administration's first Cabinet-level departure.