Story highlights The Trenton mayor's lawyer calls evidence presented against his client "weak"

Tony Mack plans to remain in his job as mayor of New Jersey's capital, says his lawyer

Mack, his brother and an associate are accused in a real estate kickback scheme

The federal charges stem from a two-year FBI investigation

The mayor of New Jersey's capital city was arrested Monday on corruption charges after being accused of accepting bribes during an undercover operation, authorities said.

The charges against Trenton Mayor Tony Mack, 46, his brother, Ralphiel Mack, 39, 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.

Mack and his brother, the head football coach at Trenton Central High School, both were released on $150,000 bail and slipped into a city vehicle after a court appearance. They were ordered to surrender their passports.

"The evidence appears to be, at this point, weak as far as Mayor Mack is concerned," Mark Davis, Tony Mack's attorney, told CNN on Monday evening. "The complaint is just full of allegations, that's all they are."

A bond hearing for Giorgianni, a sandwich shop owner, was postponed because of unrelated drug conspiracy charges.

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," according to a complaint filed in federal court.

The three defendants -- who were charged specifically with conspiracy to corrupt commerce by extortion -- employed intermediaries, "used code words and limited discussions of the scheme over the telephone" to avoid detection, the complaint said.

For example, Giorgianni would use the term "Uncle Remus" in conversations with the mayor to connote when he had received a cash payment, U.S. Attorney Paul Fishman said.

The charges stemmed from a two-year FBI investigation that incorporated two informants cooperating with law enforcement. Fishman said at least one of those moles wore a wire to record conversations for the FBI.

At a news conference before the bond hearing, Fishman pointed to repeated cases of corruption that his office has uncovered.

"Time and again, we have seen public officials in New Jersey who are all too willing to sell their power and betray the public's trust," he said.

Any trial related to Mack's case would not likely occur until next year, according to Fishman.

Mack's office declined to comment when reached by CNN. But Davis, the mayor's lawyer, stressed his client hasn't been indicted yet and should "continue to enjoy the presumption of innocence."

Based on discussions they've had, Davis said his "understanding is that (Mack) is going to remain in his (mayoral) post and continue in his official duties," as the legal case proceeds against him. The lawyer said he expects a grand jury will consider the case within 30 days.

In a separate complaint that Fishman stressed was not connected to the Macks, the government charged Giorgianni and eight others with conspiracy to distribute the highly addictive prescription painkiller oxycodone.

Fishman said Giorgianni used his business, JoJo's Steakhouse, as a front for a drug dealing operation. He's accused of storing the narcotics there, distributing the pills to dealers, then processing the cash exchanged for the painkillers.

Two months ago, agents raided the homes of Mack, his brother, and Giorgianni, before raiding Trenton's City Hall the next day.

Mack responded to the July raids by saying he had "not violated the public trust in any way, nor have I violated any of my public duties."

A Democrat who began his term in July 2010, Mack has been beleaguered by questions about public finance and accusations of cronyism.

In May, Deputy Mayor Paul Sigmund IV was arrested and charged with heroin possession and assaulting a police officer, which led to Sigmund's prompt resignation.