June 3 (UPI) -- Former NFL quarterback Johnny Manziel admitted that he "made somewhat of a decent living" by selling autographed memorabilia during his time at Texas A&M University, but he "never took a dollar" until after he won the Heisman Memorial Trophy in 2012.
"We're doing it all sneaky, we don't want to get caught, we're trying to learn from everybody else who's got caught," Manziel said during the episode that was published Thursday. "And I may or may not have gone back to this guy's condo and signed probably 10,000 pieces. He gave me three grand."
Manziel mentioned that another individual approached him during that signing session and told him he was getting "ripped off" before offering to connect him with another person who would pay him $30,000.
"So this guy is like, 'All right, go to this room at the Fontainebleau. All this stuff will be in there laid out, and when you're done, just send me a picture of all of it, I'll give you the code to the safe, the money will be in there,'" Manziel said.
The NCAA opened an investigation into Manziel before the start of his sophomore season at Texas A&M, but the organization said there was no evidence that the former star quarterback received compensation for signing autographs.
"I made somewhat of a decent living in college," said Manziel, who then challenged the NCAA to "take my [expletive] 9-4 season away and my Chick-fil-A Bowl against Duke."
When asked during the interview what he would say to the NCAA if the group tried to take away his Heisman Trophy, Manziel responded: "I never took a dollar until after I won the Heisman."
ESPN reported in August 2013 that NCAA officials were investigating whether Manziel was compensated for signing autographs at multiple locations, including in South Florida near the site of the BCS national title game earlier that year.
According to the report, several autograph dealers accused Manziel of accepting payments to sign more than 4,000 items, including footballs, photographs and mini helmets, at an event in Connecticut in January 2013.
The 28-year-old Manziel was suspended for the first half of the Aggies' 2013 season opener after the NCAA and Texas A&M announced he had violated a bylaw prohibiting student-athletes from allowing their names or likenesses to be used for commercial purposes.
That was the only punishment brought against Manziel during the 2013 season.
Manziel set multiple records in college before a short career in the NFL. He hasn't played in the professional football league since 2015.