Georgia has suspended star running back Todd Gurley indefinitely during an ongoing investigation into an alleged violation of NCAA rules, the university announced Thursday.

A person with knowledge of the investigation who spoke on the condtion of anonymity because the inquiry is ongoing told USA TODAY Sports that Gurley’s potential violation is memorabilia-related.

“I’m obviously very disappointed,” Georgia coach Mark Richt said in a statement. “The important thing for our team is to turn all our attention toward preparation for Missouri.”

SI.com reported that a person reported to Georgia’s compliance office that Gurley had signed 80 items for $400 one day last spring in Athens, Ga.

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Gurley, who leads the Southeastern Conference and ranks sixth nationally with 773 rushing yards, is viewed as one of the leading contenders for the Heisman Trophy. He also is the SEC leader in yards per carry (8.2) and is tied for the league’s touchdown lead with eight. Gurley took the lead Monday in the weekly USA TODAY Sports Heisman Survey for the first time this season.

Gurley is directly responsible for one-third of the yards gained by the Bulldogs this season and 25% of the team’s points.

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It is not known whether Gurley’s suspension is for the season or until the NCAA’s investigation is completed. It also remains to be seen, if the suspension is brief, how Heisman voters will regard Gurley. Controversy has plagued the leading candidates for the award in recent years, from Auburn’s Cam Newton to Florida State’s Jameis Winston.

Johnny Manziel, the 2012 winner of the award, saw his eligibility at Texas A&M come into question in the summer after winning the award due to a memorabilia signing investigation, but ultimately served just a half-game suspension at the start of the 2013 season.

Gurley has helped lead Georgia to a 4-1 start and a No. 10 ranking in this week’s Amway Coaches Poll. Georgia, which currently sits tied for second in the SEC East Division, plays at Missouri on Saturday in a key conference matchup.