Three autograph brokers have come forward to ESPN's Joe Schad with details about signing sessions with Johnny Manziel, but no "sources" - broker or not, anonymous or identified - have witnessed the reigning Heisman winner receive any payment.

Most recently, the third broker to come forward, requesting anonymity, said he paid the Texas A&M football player $7,500 for signing hundreds of mini and full-size Aggies helmets from Jan. 11-12. The NCAA is currently investigating another January signature incident involving a signing session with broker Drew Tieman during the BCS National Championship game in south Florida.

The third broker also provided video of Manziel signing the helmets to be used as authenticity proof for potential buyers. In the video Manziel allegedly said "you never did a signing with me" and if the broker told anyone, he would not do business with him again in the future.

The broker originally tried to sell the video to ESPN after showing it to Schad, but when they declined to buy it, he took the footage off the market. At one point in the video, Manziel is reportedly asked if he would take extra cash if he would sign with a special inscription. The QB said he would not because it led to questions in the past. Manziel is not seen accepting cash in any part of the video.

The two sources who allegedly witnessed the signing session with Tieman also said they saw no exchange of money and the second broker also said he did not pay Manziel for an autograph session before A&M's game against Alabama.

The NCAA investigation and Schad's dedicated reporting led Auburn associate professor of journalism John Carvalho to write an op-ed on AL.com about the unreliability of the sources in Schad's reports. Carvalho has also posed questions directly to Joe Schad via Twitter critical of his reporting.

"I recognize that ESPN is in a rush to stay ahead on this story," he wrote. "I am not suggesting that they gaze at their navels for days, meditating on principles while the story passes them by. But some additional steps would enhance their credibility and maybe help the reader understand the story better and trust the reporting more."

He listed problems with the ongoing report such as source credibility, granting anonymity and buying videos. He also took issue with who exactly saw the video and declined to buy it, noting that "Schad" and "ESPN" were used in the report interchangeably in regards to the details of the video.

He said if one of his students wrote the article, he would return it with a comment in the margin saying, "networks don't view videos, people do."

Further, other college athletes have had similar signing situations without any incident. According to SB Nation, South Carolina defensive star Jadeveon Clowney, Alabama's QB AJ McCarron and many more have plenty of autographs being sold on eBay. South Carolina investigated Clowney's eBay signatures and found nothing wrong.

Paying NCAA Division I athletes for their play on the field, helping their sport generate billions of dollars in revenue, has been a hotly debated issue of late. In fact, former Heisman winner Desmond Howard is currently battling a lawsuit for using an iconic photo of Desmond Howard.

In short, a photographer claims he has the rights to a photo of Howard's famous Heisman pose after his touchdown return against Ohio State in 1991. The photo has been used in magazines, on video game covers, in commercials and more. Howard became entangled when he used it on his website without the photographer's permission.

"It's costing me [$100,00] to defend myself over a picture ... of me," Howard told CBS Sports. "I never sold the picture, I'm just being lumped into it. His entire business is a picture of me."

Despite this legal battle and that of Ed O'Bannon, it is still illegal for college athletes to be compensated for their play and for their signatures. Manziel could be ineligible for the upcoming season pending the NCAA's investigation.