MIAMI -- The NCAA is investigating whether Heisman Trophy winner Johnny Manziel was paid for signing hundreds of autographs on photos and sports memorabilia in January, "Outside the Lines" has learned. Two sources tell "Outside the Lines" that the Texas A&M quarterback agreed to sign memorabilia in exchange for a five-figure flat fee during his trip to Miami for the Discover BCS National Championship. Both sources said they witnessed the signing, though neither saw the actual exchange of money.

Seen here is one of the hundreds of autographed photos Johnny Manziel allegedly was paid to sign, as verified by authentication company JSA. Darren Rovell/ESPN

Three sources said Manziel signed photographs, footballs, mini football helmets and other items at the request of an autograph broker named Drew Tieman. Two sources, who are aware of the signing arrangement, told "Outside the Lines" that Tieman approached Manziel on Jan. 6, when he landed at Fort Lauderdale-Hollywood International Airport to attend the game between Alabama and Notre Dame the next day.

After that meeting, three sources said, Manziel, accompanied by his friend and personal assistant Nathan Fitch, visited Tieman's residence and signed hundreds of items in the main room of the apartment despite the fact that there were many people in the room. Before Manziel left South Florida, after taking in the title game, he signed hundreds of autographs more, one source said.

The source also told "Outside the Lines" that James Garland, the NCAA's assistant director of enforcement, in June contacted Tieman and at least one person associated with the signings. The source said Garland, who did not return calls from "Outside the Lines" for comment, told the person that he wanted to talk about Manziel signing items that had appeared for sale on eBay. An NCAA spokeswoman cited NCAA policy to "Outside the Lines" and declined to comment.

If the NCAA investigation finds that Manziel has violated NCAA Bylaw 12.5.2.1 -- accepting money for promoting or advertising the commercial sale of a product or service -- he could be ruled ineligible.