Ira Thomas, an Orleans Parish School Board member who has been at the center of the board’s most contentious debates over the past three years, was accused Friday of accepting a bribe, another black mark for the city’s political class and for a board that became notorious before Hurricane Katrina for rampant corruption.

U.S. Attorney Kenneth Polite Jr. said Thomas has been charged with taking $5,000 in cash in exchange for helping a janitorial contractor win favorable treatment from the school district. Polite said the bribe was disguised as a campaign contribution.

“This community will no longer tolerate public corruption from its public officials, period,” Polite said. “Our investigation is ongoing.”

Thomas, the chief of campus police at Southern University at New Orleans, resigned his seat on the board as well his police post Friday.

He was charged in a federal bill of information rather than a grand jury indictment — usually a sign that a defendant is cooperating and intends to plead guilty. He did not immediately return a phone call seeking comment.

The School Board has taken pains to distance itself from the pre-Katrina era, when corruption and mismanagement sank the district into a financial morass and thwarted attempts by successive superintendents to raise test scores from the bottom of state rankings.

The allegations against Thomas certainly don’t help matters.

The bill of information outlining the charges against Thomas describes what appears to have been a sting operation carried out by federal authorities. It says an unidentified cooperating witness approached someone who worked for the School Board, identified only as “Employee A,” in September 2013. Employee A offered the cooperating witness a janitorial contract in return for a kickback.

Those two people then allegedly met to discuss the contract with Thomas, who was running for sheriff at the time and struggling to raise money for his campaign, as well as someone identified as “Private Citizen B.” That conversation was surreptitiously recorded by the cooperating witness.

The bill says the witness gave Private Citizen B the $5,000 in December 2013 and videotaped the handoff. Then Private Citizen B allegedly deposited the cash in his own bank account and gave Thomas a share in cash. The money — the documents don’t say how the money was split — never made it to Thomas’ campaign account, and he never reported receiving the contribution.

Finally, about a year later, Thomas and Employee A were allegedly recorded on the phone discussing how to rig the bidding process for the janitorial contract in order to make sure the cooperating witness got the job.

The government’s bill does not say what the value of the janitorial services contract was, except that it was worth more than $5,000. Nor does it say whether it was ever awarded. It’s not clear how Thomas planned to guarantee that the janitorial firm would get the deal.

Thomas emerged as a divisive figure on the board after a failed bid to win the job of board president in 2012. After that, the board split into stark factions, and Thomas started attacking interim Superintendent Stan Smith for the way he was managing construction contracts, a stance that immediately raised suspicions about his motives.

The new divisions also stirred concerns about the board’s future.

In the past few years, the independent charter schools operating under the state-run Recovery School District, which took over all but a handful of the city’s public schools after the storm, have mostly improved their academic standing above the “failing” mark. As they do so, some have become eligible for transfer back to local control under the board.

But those schools have been wary of getting involved in the board’s contentious politics and are mindful of its history. Just this week, the board was trying to finalize a contract with a new superintendent, Henderson Lewis, in the hopes of signaling a new phase of stability and luring more schools back to the local fold.

On Friday, other members of the board were quick to publicly welcome the U.S. attorney’s efforts to target corruption in their ranks.

“I support U.S. Attorney Ken Polite and agree that public corruption must not be tolerated on any level, and I am saddened that distractions like this take away from our important focus on improving public education for the children of New Orleans,” OPSB President Seth Bloom said in a prepared statement. He added, “At the same time, as a criminal defense attorney, I recognize that Mr. Thomas is innocent until proven guilty, and I await the resolution of this matter.”

Another board member, Woody Koppel, said, “I’m glad the U.S. attorney has done this. The record has been clear. There are people on this board who believe in transparency and honesty, and their voting record reflects that.”

Friday’s announcement was the first new charge of public corruption Polite’s office has issued since he took over for Jim Letten more than a year ago.

FBI Special Agent in Charge Mike Anderson said the probe is ongoing, describing it as a “real-time” investigation, unlike that of former New Orleans Mayor Ray Nagin, who is now serving a jail sentence for public corruption. In Nagin’s case, investigators pieced together official misdeeds after the fact.

The irony that Thomas is accused of trying to fix a janitorial contract won’t be lost on anyone who recalls the Orleans Parish School Board before Katrina.

By the time of the storm, public schools in New Orleans had become notorious for squalid bathrooms and uncut grass. In 2009, the head of a company called AME Services that did janitorial work for the board testified in federal court that former board President Ellenese Brooks-Simms, whose son-in-law worked for the company, had acted as his “protector,” blocking numerous attempts by superintendents to get the company fired.

Similar questions came up during the trial of Mose Jefferson, a political operative and the brother of then-U.S. Rep. William Jefferson.

Brooks-Simms, a key witness for the government, had pleaded guilty to accepting $140,000 in bribes from Mose Jefferson.

In exchange, she said, she pushed the board to purchase a computer-based algebra curriculum that Mose Jefferson was peddling.

While Brooks-Simms pleaded guilty, Jefferson argued at trial that he simply loaned her the money because she was a friend, and part of his defense was that Brooks-Simms — as one of seven School Board members — was not in a position to deliver the contract. The board unanimously voted to purchase the product Jefferson was selling, called I CAN Learn.

Jefferson was convicted and sentenced to 10 years in prison, where he died in 2011.

Staff writers Gordon Russell and John Simerman contributed to this report.