METAIRIE, La. -- New Orleans Saints coach Sean Payton expressed his astonishment on Twitter after Fox Sports reported Sunday that former Saints whistleblower Mike Cerullo now works for the NFL office.

Cerullo, a former defensive assistant for the Saints, provided key evidence to the NFL to kick-start its bounty investigation against the team in 2011, and the Saints dismissed him as a "liar" with a grudge against them for being fired.

Cerullo spent the past several years as Princeton's director of football operations before being hired by the league as a director of football administration this past summer.

NFL spokesman Michael Signora said Cerullo works closely with senior vice president of football administration and club services Rod Graves on matters related to club administration and development, as well as supporting efforts involving college all-star games and project management.

The Saints, however, are skeptical about Cerullo receiving a perceived reward from the league -- especially since they made it clear during the bounty investigation that they felt like he did a poor job in New Orleans.

Sean Payton's behavior toward the officiating crew Thursday in the Saints' loss to the Falcons is being reviewed by the NFL. Kevin C. Cox/Getty Images

However, Signora confirmed that Cerullo is not involved with any disciplinary matters that would represent a conflict of interest -- such as the review currently taking place into whether Payton should be punished after his Thursday night penalty for unsportsmanlike conduct toward officials.

Cerullo, who was not retained by the Saints after the 2009 Super Bowl season, sent the NFL an email in November 2011 calling the Saints a "dirty organization" and saying he had proof that assistant head coach Joe Vitt had lied to the league about the existence of a bounty program.

The NFL eventually suspended Payton for one full season and handed out severe punishments to Vitt, general manager Mickey Loomis and the entire organization in the form of fines and lost draft picks. Four players were also initially punished -- including a full-year suspension for linebacker Jonathan Vilma -- though all of the player punishments were eventually overturned on appeal by former NFL commissioner Paul Tagliabue.

When asked during those appeal hearings what motivated him to come forward, Cerullo said: "I was angry for being let go from the Saints. ... I was angry at Joe Vitt, and I wanted to show that I was fired for lying and I witnessed Joe Vitt lying and he still had a job."

Vitt, meanwhile, testified that Cerullo lied about family emergencies while taking two personal leaves of absences during that 2009 season and referenced a time when Payton needed to ask for police protection for his family when he was out of town because he considered Cerullo a threat. Vilma's attorneys made similar accusations about Cerullo's work performance.

Cerullo later sent a letter to Tagliabue saying he had been "vilified and subjected to slanderous lies" after his name was revealed publicly. And after Cerullo's name was publicly revealed in September 2012, the NFL released a statement saying he "should be commended for coming forward."

"The information and detail he provided was credible and has since been confirmed in numerous respects both by other witnesses and by supporting documents," the NFL statement read. "It is unfortunate that some have sought to unfairly attack his integrity rather than give attention to the substance of his declaration."