NEW ORLEANS (AP) — A Louisiana businessman linked to a federal probe of former New Orleans Mayor Ray Nagin pleaded guilty Wednesday to making a $50,000 payoff to a former city official in exchange for favorable treatment for his business interests.

Authorities haven’t identified the official Frank Fradella allegedly conspired to bribe, but court documents said the official served from May 2002 to May 2010 — a period matching Nagin’s tenure in office.

Prosecutors said Fradella, 56, of Covington, provided truckloads of free granite to the official. Nagin and his two sons obtained a contract to install granite countertops for local Home Depot stores after Hurricane Katrina struck in 2005.

Fradella also “facilitated” a consulting agreement and monthly payments of more than $10,000 to the official after he left office, according to a court filing Wednesday.

In exchange, the official approved city contracts involving Fradella’s business interests and used his office to promote Fradella’s company.

Nagin has not been charged. His attorney didn’t immediately return a call seeking comment Wednesday.

Fradella faces up to seven years in prison under the terms of his plea agreement with prosecutors. The charges to which he pleaded guilty carry a combined maximum sentence of 15 years in prison. U.S. District Judge Susie Morgan isn’t bound by the terms of the plea agreement, and Fradella can withdraw his guilty plea if she rejects the deal.

Fradella also pleaded guilty to a securities fraud charge that originated in Dallas, where he was indicted in May. The Texas case was transferred to New Orleans after Fradella cut his deal with prosecutors.

Morgan set Fradella’s sentencing for Sept. 26.

Fradella’s attorney, Randy Smith, and U.S. Attorney Jim Letten wouldn’t name the person who is identified only as “Public Official A” in court papers. Letten said Justice Department policies prohibit him from naming the official because the case is part of an ongoing grand jury probe.

“We will continue to follow the evidence wherever it takes us and will not stop until that is complete,” Letten said.

Fradella’s attorney revealed Tuesday that his client had a plea deal and is cooperating with federal authorities, but Wednesday’s court filing offered new details about the bribery scheme.

It said funds from the $50,000 payoff were funneled through a bank account controlled by a board member for one of Fradella’s companies to conceal the payment. The official provided corporate ownership documentation to the board member to “create the illusion of legitimacy,” according to the filing.

Smith said Tuesday that it was “pretty obvious” who the unidentified official is.

“If it walks like a duck and talks like a duck, it’s probably a duck,” Smith said. “I don’t have the right to name the duck. Only the government can name it.”

Fradella was CEO of Home Solutions of America Inc., a publicly traded disaster reconstruction firm.

Aaron Bennett, a businessman who pleaded guilty last year in a separate bribery case, told The Times-Picayune he introduced Nagin to Fradella specifically to help the mayor get the Home Depot work. Fradella’s company received millions of dollars in city contracts for repair work at Louis Armstrong New Orleans International Airport and in the French Quarter after Katrina, the newspaper reported.