There’s no arguing what Mark Dantonio did for the Michigan State football program over the last 13 years. However, there are some questions surrounding the timing of his decision to step down as the Spartans coach.

Dantonio announced his decision to retire on Tuesday, releasing a statement on Twitter.

“Today marks one of the most difficult decisions that I have ever made here at Michigan State,” Dantonio wrote. “I would first like to thank our fans, alumni, and our administration; both past and present staff and especially our current and past players and coaches for all their support, hard work and dedication over these past 13 years. You have truly helped make my dreams come true.”

The move comes less than a month after a retention clause in his contract paid him an extra $4.3 million and less than a day before National Signing Day on Feb. 5.

It also comes a day after a lawsuit brought by a former staffer, Curtis Blackwell, alleges the now-former coach broke NCAA rules on an in-home visit and potentially revealed violations related to a booster “providing the parents of star recruits jobs/employment upon signing to play for MSU.”

Last week, Dantonio’s lawyer said any allegations of NCAA violations were “false.”

Dantonio, who will stay within the MSU athletic department, finishes his career as the Spartans’ all-time winningest coach with 114 victories, notching three Big Ten championships, a Rose Bowl win and a 2015 College Football Playoff appearance along the way.