NCAA investigators spent a large chunk of Sunday with Johnny Manziel, questioning the Texas A&M quarterback about allegations from memorabilia dealers that he accepted payments for autographs, a source familiar with the investigation told ESPN.com on Monday night.

The governing body's officials met with Manziel, the reigning Heisman Trophy winner, for nearly six hours on the College Station, Texas, campus, the source said.

Manziel denied in the meetings that he ever took money for signing autographs, CBSSports.com reported, citing sources close to the player.

It was unclear whether the NCAA was satisfied with the initial meeting with Manziel or if it would require additional time with the redshirt sophomore. Texas A&M's season begins Saturday, at home against Rice. Manziel has taken all of his practice reps with the first team, and barring a decision by the NCAA, the school has until kickoff to make any decision on whether he starts.

Attorney Jim Darnell, hired by Manziel's family, did not return calls to ESPN on Monday night seeking comment.

Texas A&M athletic director Eric Hyman said Monday night that he'd instructed everyone in the program not to talk about Manziel. Reporters asked anyway on Tuesday, and coach Kevin Sumlin responded by saying: "We're not discussing that."

Earlier this month, ESPN reported that the NCAA was looking into whether Manziel was paid for signing autographs at several locations, including in South Florida around the BCS title game.