(AP) — Mississippi football coach Hugh Freeze has resigned after five seasons, bringing a stunning end to a once-promising tenure.

The school confirmed Freeze’s resignation in a release Thursday night. Assistant Matt Luke has been named the interim coach. A press conference was scheduled for late Thursday.

The Rebels had a quick rise under Freeze, recruiting at a high level and reaching an apex with a Sugar Bowl victory over Oklahoma State following the 2015 season.

But an NCAA investigation — alleging 21 charges of academic, booster, and recruiting misconduct — has overshadowed much of that success, especially over the past year. The school has already self-imposed several penalties, including a one-year postseason ban for the upcoming season.

Freeze — who was making more than $5 million per year — had a 39-25 record over five seasons, including a 19-21 mark in the Southeastern Conference.

The 47-year-old Freeze’s shocking exit — just a few weeks before preseason camp begins — completes a stunning fall for a coach considered one of the profession’s rising stars a few years ago.

Freeze took over after Houston Nutt was fired during a miserable 2011 season that ended with a 2-10 record. Ole Miss immediately improved under Freeze, finishing 7-6 in 2012 and winning the Birmingham Bowl.

The Rebels continued to surge on the field and on the recruiting trail over the next several seasons. They signed some of the nation’s top recruits in 2013, including defensive lineman Robert Nkemdiche, receiver Laquon Treadwell and offensive lineman Laremy Tunsil. They helped push the program to eight wins in 2013, nine in ‘14 and a 10-3 record in ‘15.

But Ole Miss’ newfound ability to recruit at a high level drew the attention of the NCAA, which was already investigating the school for a handful of violations that occurred during Nutt’s tenure.

The school has received two Notice of Allegations letters from the NCAA over the past two years. The first alleged 13 rules violations, including nine that were classified as Level I, which the governing body deems the most serious.

But the case expanded in April 2016 after Tunsil became the story of the NFL draft after a bizarre video of him smoking from a gas mask-bong contraption was posted on his Twitter account just before the selections began.

There was also a post on Tunsil’s Instagram account showing an alleged text conversation with a football staff member about arranging payment for bills.

Though the NCAA didn’t appear to find much from that particular exchange, the governing body did reopen its investigation, sending a second NOA earlier this year that expanded the case to 21 allegations, including 17 that are Level I.