An undercover FBI agent posing as a wiseguy infiltrated the Gambino organized crime family for two years with an act so convincing he was considered for membership, authorities said Wednesday.

"Had we left him out on the street much longer, the Gambino family ranks would actually have increased by one," Pasquale D'Amuro, head of the FBI's New York office, said at a Manhattan news conference announcing more than 30 arrests in a racketeering investigation.

The unidentified agent "risked his life as a mole for the better part of two years after he was put on record" as a family associate, said U.S. Attorney David Kelley.

Among those named in a 53-count indictment were Arnold "Zeke" Squitieri (search), of Englewood Cliffs, N.J. — who allegedly took over as acting Gambino boss after Peter Gotti (search) was convicted in two separate trials last year — and reputed underboss Anthony "The Genius" Megale, 51, of Stamford, Conn.

The indictment alleges Squitieri, Megale and other defendants made millions of dollars through extortion, loansharking, illegal gambling and other crimes during the past decade. Some of the crimes — which included the shakedown of a radio station and a beating at Bloomingdale's — were plotted at a nursing home, court papers said.

Squitieri was awaiting arraignment in federal court in Manhattan; a call to his attorney was not immediately returned. Megale, already in custody on a separate racketeering indictment in Connecticut, denies he's underboss, said defense attorney Stephan S. Seegar. Both defendants face up to 20 years in prison if convicted.

D'Amuro credited the undercover agent with making hundreds of secret recordings revealing the family's inner-workings. It was a feat not seen since FBI agent Joe Pistone's work in the Bonanno family 25 years ago under the alias Donnie Brasco (search), he said.

Like Brasco, the agent "was told by a high-ranking member of the crime family that he would be proposed for induction," D'Amuro said.

Defense attorney Stephan E. Seeger said he told Megale about the charges Wednesday morning but said they had not seen the indictment. Megale's attorneys have maintained that he is not the underboss of the Gambino family.

"I don't even know what that means," Seeger said. "I'm not going to dignify it because it's just part of the allegations the government makes. The system is set up to give Mr. Megale the right to be heard."

The radio station — which is located in the city but not named in court papers — was among several businesses allegedly targeted for extortion. The FBI said the station was forced to run advertisements and promotions for Gambino-controlled businesses.

Authorities also allege that two of the defendants attacked a third mobster earlier this year in the housewares department at a Bloomingdale's (search) in White Plains, N.Y. The victim was severely beaten with a candlestick.

Some of the defendants allegedly tried to avoid scrutiny by holding meetings at the bedside of the comatose son of a mobster at a nursing home in New Rochelle, N.Y.