There was more reckoning on Friday from the failure to stop Lawrence G. Nassar, who is accused of serially abusing more than 150 young women while he was a doctor at Michigan State University and for the national women’s gymnastics team. The fallout stretched from the university to U.S.A. Gymnastics to Capitol Hill.

At Michigan State, Mark Hollis, the university’s athletic director, abruptly announced his resignation just two days after the university president, Lou Anna Simon, resigned.

“This was not an easy decision for my family, and you should not jump to any conclusions,” Mr. Hollis said in a statement in which he also declared, “I am not running away from anything.”

A lawyer for the university has said an inquiry had found no evidence that high-ranking administrators knew about Dr. Nassar’s conduct before 2016. But that inquiry has not been made public in full, and The Detroit News reported that more than a dozen university staff members had heard of reports before then. Michigan State investigated Dr. Nassar after a recent graduate made a Title IX complaint against him in 2014, and the school cleared him.