In a development that rocked the world of college football, University of Mississippi Coach Hugh Freeze resigned Thursday night, effective immediately. The move came amid reports that he had used his school-issued phone to place a call last year to an escort service.

Ole Miss confirmed the resignation and announced that offensive coordinator Matt Luke had become the interim head coach. Freeze’s departure brings an abrupt end to a five-year stint in Oxford that had earned the 47-year-old Mississippi native widespread acclaim — but also resulted in a pending hearing with the NCAA’s Committee on Infractions and a self-imposed, one-year bowl ban.

Yahoo Sports and USA Today reported on the call to the female escort service, which was brought to the attention of Ole Miss administrators by an attorney for former Rebels coach Houston Nutt, who is suing the school for violating the terms of his severance agreement. The call made by Freeze, who replaced the fired Nutt in 2011, took place in January 2016 and reportedly lasted around a minute.

In a news conference Thursday, Ole Miss Athletic Director Ross Bjork said that school officials had discovered “a pattern of personal misconduct inconsistent with the standards we have come to expect from the leader of our football team.” He noted that the number for the escort service appeared to have dialed just once from Freeze’s phone, but in looking further through his call logs, officials found a “concerning pattern.”

Freeze told Yahoo last week that he had “no idea” why the call was on his phone, saying that it “might have been a misdial.”  The coach claimed that he’d had the chance to redact numbers from his phone records, after Nutt’s attorney filed a freedom of information request to obtain them, and the fact that he left that number unredacted showed that there was “nothing to it.”

“If I was trying to hide something, I would have,” Freeze said. “That call shows up nowhere else on my records. There is no story to that one.”

According to USA Today, Nutt’s attorney, Thomas Mars, sent an email to Mississippi’s general counsel in which he referred to a “phone call Coach Freeze made that would be highly embarrassing for all of you and extremely difficult to explain.”

The NCAA is set to rule on 21 alleged infractions committed by the Rebels, including charges of charges of academic, booster, and recruiting misconduct. Former Ole Miss offensive lineman Laremy Tunsil confirmed during last year’s NFL draft that he had received impermissible benefits from a staffer for the program.

Nutt’s lawsuit accuses Freeze and other Ole Miss officials of attempting to blame many of the infractions on him, thus tarnishing his reputation and hampering his ability to find employment. Until Thursday, the school had shown staunch support for Freeze, and Bjork said that the coach spoke of his decision to resign in “raw, emotional, tough meetings” with players and staffers.

Bjork claimed that had Freeze not resigned, the school would have exercised a “moral turpitude” clause in the coach’s contract and fired him. “It’s a sad day,” Bjork said.

Taking over a Rebels program that gone 2-10 the previous season, and 1-15 in the SEC over the previous two seasons, under Nutt, Freeze went 7-6 his first season. He increased his win total by a game each year, cresting with a 10-3 season in 2015 and a Sugar Bowl win over Oklahoma State.

The Rebels tumbled to 5-7, 2-6 in the SEC, last season, leaving Freeze with a record of 39-25 overall, 19-21 in conference play.