(CNN) -- The mayor of New Jersey's capital city and two other defendants who have been embroiled in corruption allegations since September were indicted by a federal grand jury Thursday on seven new counts, according to court documents.
The charges against Trenton Mayor Tony Mack, 46, his brother, Ralphiel Mack, 40 and business associate Joseph A. "JoJo" Giorgianni, 63, stem from an alleged kickback scheme to sell city-owned land to investors for significantly less than the assessed value.
The three initially were charged in September following a federal investigation.
The charges stemmed from a two-year FBI investigation that incorporated two informants cooperating with law enforcement.
The investigation "revealed evidence of a conspiracy among these defendants and others to corrupt certain functions of Trenton City government in favor of purported developer seeking to build a parking garage on city owned property in exchange for cash payments totaling approximately $119,000," said the official complaint filed in federal court in September.
At that time, all three were charged with "one count of conspiracy to obstruct commerce by extortion under color of official right related to the $119,000 extortion scheme" court documents said. The indictment returned Thursday added seven other counts including bribery and extortion.
The indictment stated there are two unnamed witnesses who are cooperating with the federal government.
Over the course of eight months, the three defendants allegedly agreed to accept the $119,000 in several installments of cash payments, the indictment stated.
The mayor's office did not immediately return requests for comment.
But Mayor Mack's defense attorney, Mark Davis, said he was feeling confident about the case moving forward.
"We knew this day was coming and we're happy it did," Davis said on Thursday. "Now we can begin our trial preparations."
In July, agents raided the homes of Tony Mack, his brother, and Giogianni, before raiding Trenton's City Hall the next day.
Mayor Mack is a Democrat who began his term in July 2010.
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