Georgia tailback Todd Gurley has been suspended indefinitely pending an investigation into an alleged violation of NCAA rules, the school announced Thursday.

A source told ESPN's Joe Schad that the NCAA investigation centers around whether Gurley was given money for autographs, memorabilia or the use of his likeness. Georgia officials did not reveal the alleged violation.

"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."

One source in the autograph industry told ESPN's Darren Rovell that it was known that Gurley was seeking between $8 and $25 per signature, charging less to an autograph dealer if he signed more pieces.

Noted autograph authentication company James Spence Authentication (JSA), meanwhile, has authenticated at least 500 Gurley signed items with certificates of authenticity, including more than 300 jerseys, more than 30 mini-helmets, more than 70 photos and even 10 baseballs and nine Nike cleats, ESPN has learned. ESPN verified the authentication through JSA's website, which allows the purchaser of an authenticated item to type in the serial number on the card provided with the item and match it with the authenticator's records.

Items with serial numbers L39251 to L39551 all showed up as Gurley-signed jerseys, meaning it was likely done at one time and sent in by the same person or company. Whether Gurley received money for them, however, is unknown.

A representative with the company could not immediately be reached for comment.

Georgia announced Gurley's suspension Thursday, two days before the No. 13 Bulldogs (4-1, 2-1 SEC) face No. 23 Missouri (4-1, 1-0) in a crucial Eastern Division game.

Big Shoes To Fill With Todd Gurley suspended indefinitely, Georgia will turn to a running back corps that has not gotten many touches this season. Gurley's 773 rushing yards this season are more than all four backs combined. RB Carries Rush Yards N. Chubb 31 224 S. Michel 23 223 K. Marshall 12 24 B. Douglas 8 47 --ESPN Stats & Information

Gurley practiced with the Bulldogs on Monday, Tuesday and Wednesday, but it is unclear whether he practiced Thursday.

On Friday, Georgia was no longer selling Gurley No. 3 jerseys on its official website. The school was previously selling two Nike jerseys -- one for $134.95 and one for $89.95.

Gurley leads the Bulldogs with 773 yards rushing and eight touchdowns, averaging 8.2 yards per carry. In addition, he has 11 receptions and a 100-yard kickoff return for a TD.

The junior established himself as a leading Heisman contender with several signature games and moments, including a school-record 293 all-purpose yards in a season-opening victory over Clemson, not to mention a hurdler-like leap over a Tennessee defender to pick up an extra 10 yards.

He ran for 163 yards and two TDs against Vanderbilt last week while also completing a 50-yard pass -- Georgia's longest of the season. Gurley is the conference's leading rusher with 154.6 yards per game, and his 194.6 all-purpose yards ranks second nationally behind Nebraska's Ameer Abdullah (195.8).

With 3,147 rushing yards, Gurley needs 86 to pass Garrison Hearst for second on the school's all-time list.