A Michigan State University trustee has dissented from the board’s public support for its president, calling on Saturday for her to resign amid questions about her knowledge of complaints about Dr. Lawrence G. Nassar, a former university doctor who was accused of molesting scores of female athletes.

The trustee, Mitch Lyons, broke ranks with the eight-person board one day after it issued a statement declaring its support for the president, Lou Anna K. Simon, who was appointed in 2005.

In his statement, Mr. Lyons said he had been “very troubled” since the board’s remarks. He said that although he agreed with the board’s request for the state’s attorney general to review the situation, he believed that the public had “lost confidence” in Dr. Simon — and that the loss was “irreparable.”

Noting that he did not think Dr. Simon “knowingly engaged in any cover-up or criminal wrongdoing,” Mr. Lyons said the university’s institutional accountability had nonetheless been compromised.