Lazzari said he loved the challenge of going up against smart mobsters and their big-time lawyers. He loved it so much, in fact, that the day he retired in 1979, fellow agents had to pry him away from wiretaps and literally push him out the door.

"I still miss it," Lazzari, now 82, recalled last week. "I really enjoyed it thoroughly. I looked forward to going to work every day."

Yesterday marked the 100th anniversary of the nation's premier law enforcement agency, amid a month of national and local celebrations. And on Thursday night, Lazzari will be among the nearly 600 agents, employees, business and community leaders, and fellow law enforcement officials at a gala Center City banquet.

They will be toasting the successes of the past even as they embrace the challenges of the present and the future in the changing world since the Sept. 11, 2001 terrorist attacks.

Terrorism and counterintelligence remain the top national criminal priorities of the FBI, followed by cyber crime and public corruption.

In Philadelphia, the FBI has long been in the thick of some of the city's most memorable corruption investigations - from the Abscam influence-peddling scandal of the 1980s to the corruption case that burst into view in 2003 with the discovery of that infamous "bug" in Mayor John F. Street's office.

The FBI has targeted successive leaders of the Philadelphia-South Jersey mob, put three City Council members behind bars over the last 20 years, and tracked the Junior Black Mafia, international art thefts, and dentist-turned-drug dealer Larry Lavin, who ran a major cocaine operation.

The FBI also has been part of a strategic shift to federal scrutiny of neighborhood gun and drug crimes that once had been handled almost exclusively by local authorities.

"It was the first organization to really embrace the notion of smart, educated investigators, and as such, I think the breadth and depth of their investigations was really a landmark leap in the way investigations were conducted," said JoAnne A. Epps, a former federal prosecutor in Philadelphia who is now dean of Temple University's law school.

Epps credited the FBI with wreaking havoc on the Philadelphia-South Jersey crime family, and also with aggressively going after public corruption - without a political agenda or partisan interests.

"They've never been put off by political issues," said Epps. "They've been fair - I can certainly say that about this office - and objective in their investigations."

The agency was among the first to require a college degree for agents, and it has long attracted accountants, lawyers and linguists as well as veteran police officers. The process of becoming an agent is intense, with fledgling agents put through a rigorous four months of training at FBI school in Quantico, Va.

Former federal prosecutor Richard L. Scheff, who is now a white-collar defense lawyer in Philadelphia, attributed the FBI's success to an arsenal of tools, including court-authorized wiretaps, the power to issue subpoenas all over the country, and a global approach to complex financial investigations.

"Crime has become global, and it knows no borders," he said.

Scheff, who supervised the corruption unit in the U.S. Attorney's Office, said corruption cases require a special touch and a level of political independence that is more difficult for elected prosecutors than for career agents.

"Without the FBI and the expansive scope of the federal laws which they enforce, efforts to combat public corruption at the state and local level would be much more difficult and less effective," said Scheff, who prosecuted the 1986 case against leaders of Roofers Union Local 30-30B, which also led to charges against city judges who accepted cash from the union.

Lazzari, meanwhile, said the bureau had evolved since he joined, first as a fingerprint clerk in 1947, then as an agent in 1955.

Back in those days, he said, the FBI was a "lily white" bastion, and when agents needed a female to help out on an undercover assignment, they had to ask a stenographer to go along.

The look was more formal, too - agents wore dark suits, crisp shirts and ties, and, for a time, fedora hats were required. Lazzari said the expression was: "You looked the part. You act the part. You were the part."

Today, about 20 percent of agents are minorities and 20 percent are women, according to FBI spokeswoman Jerri Williams.

"I think for the better, it changed," said Lazzari, who lives in Delaware County.

Crime, too, has changed, he said. The mob figures from back in his days were crafty and had lots of money, Lazzari said.

"They were wild, but they were not as wild as the drug dealers today," he said.