MONTGOMERY, Ala. -- The NCAA said it found no major violations committed by Auburn regarding Cam Newton or other pay-for-play allegations and has concluded multiple investigations of the football program.

The NCAA released a statement Wednesday saying it has closed its 13-month investigation into Auburn's recruitment of the Heisman Trophy-winning quarterback, whose father shopped his services to another school for up to $180,000.

The investigation hovered over the program during the Tigers' national championship run.

The NCAA also cleared Auburn in allegations by four former players that they received payments during their recruitment or careers.

The NCAA notified Auburn of the decision Tuesday in a letter from associate director of enforcement Jackie A. Thurnes. Auburn released it Wednesday.

"As I've said many times, I feel very confident about the way we run this program," Tigers coach Gene Chizik said Wednesday night. "I've said many times that we haven't done anything wrong, so quite frankly I moved on a long time ago."

He said he spoke briefly to Newton -- now with the NFL's Carolina Panthers after a season at Auburn, after practice Wednesday, "but we did not talk about that at all. I just told him I'm proud of him and he's going to watch the (Florida) game on Saturday and he's excited about it."

Chizik said he didn't address the NCAA's notification with his team, but he appreciated that the governing body made the decision public.

Thurnes said NCAA enforcement staff and the university conducted more than 50 interviews into whether Newton was paid to sign with Auburn and examined documents including bank records, tax filings and phone and email records.

"The NCAA enforcement staff is committed to a fair and thorough investigative process," the NCAA said in a statement. "As such, any allegations of major rules violations must meet a burden of proof, which is a higher standard than rampant public speculation online and in the media. The allegations must be based on credible and persuasive information and includes a good-faith belief that the Committee on Infractions could make a finding.

"As with any case, should the enforcement staff become aware of additional credible information, it will review the information to determine whether further investigation is warranted."

The NCAA agreed with Auburn's self-report from Nov. 30, 2010, that Cecil Newton and the owner of a scouting service, Kenny Rogers, shopped Cam Newton's services to Mississippi State out of junior college, but that there was no evidence the player or Auburn knew about it.

Newton led the Tigers to a national title and was the No. 1 NFL draft pick by Carolina, which made him an instant starter. The final months of his spectacular season were clouded by the allegations, though.

Auburn declared Newton ineligible four days before the SEC championship game, and the NCAA reinstated him the following day saying there was not "sufficient evidence" that Cam Newton or Auburn knew of the attempts to cash in on his talent.

More allegations surfaced in March when the four former Auburn players raised additional claims of wrongdoing in the program.

Raven Gray, Stanley McClover, Chaz Ramsey and Troy Reddick told HBO's "Real Sports with Bryant Gumbel" that they received thousands of dollars while being recruited by or playing for the Tigers.

They said the cash was delivered in book bags, envelopes and even handshakes. Ramsey played at Auburn most recently, in the 2007 season.

Thurnes said the NCAA interviewed Gray and his family members and friends and that his claims were not substantiated "and in some instances were disputed by others."

The other three players interviewed by HBO declined to speak with the NCAA, which said "their lack of cooperation and lack of any other information" left insufficient reason to conclude that any violations occurred.

Chizik, who was defensive coordinator during the careers of Reddick and McClover, had dismissed the report as "pure garbage." Auburn hired outside counsel to investigate the claims.

"We appreciate the NCAA and thank them for their professionalism and thoroughness during this exhaustive investigation," Auburn athletic director Jay Jacobs said. "We are pleased to put this matter behind us."

Auburn spent $183,667 in attorney's fees on the Newton case and $82,463 for the other investigation through August, the university said Wednesday in response to an August 18 opens records request from The Associated Press.