At the heart of his success was an innovative legal strategy employing the federal Racketeer Influenced and Corrupt Organizations Act, or RICO — a Nixon-era law that allowed prosecutors to go after multiple members of a criminal enterprise in one case.

One political observer watching Giuliani’s rise was former New York City Mayor Bill de Blasio, who worked for Mayor David Dinkins both in City Hall and on two campaigns.

“As an Italian American during his earlier years as U.S. Attorney, he was cleaning up the Teamsters and going after the Mafia. I had a sense of admiration — and I was not a guy who loved Republicans,” said de Blasio, who later soured on Giuliani, to put it mildly.

On Monday night, Giuliani himself was named in a RICO case being brought in Georgia by the Fulton County district attorney, who accuses the former New York City Mayor — along with former President Donald Trump and 17 others — of conspiring to overturn the 2020 election.

That the same legal strategy Giuliani pioneered is now being used against him is more than ironic. The RICO statutes gave rise to his political career. Now they threaten to be his undoing.

Giuliani, along with Trump, has sharply criticized the indictment and maintained his innocence. And the former mayor has said he was simply acting as Trump’s attorney during the events of 2020.

“This is an affront to American Democracy and does permanent, irrevocable harm to our justice system. It’s just the next chapter in a book of lies with the purpose of framing President Donald Trump and anyone willing to take on the ruling regime,” Giuliani said in a statement released Tuesday. “They lied about Russian collusion, they lied about Joe Biden’s foreign bribery scheme, and they lied about Hunter Biden’s laptop hard drive proving 30 years of criminal activity. The real criminals here are the people who have brought this case forward both directly and indirectly.”

According to Giuliani, the idea to go after mob leaders by using a RICO case was first discussed in his office in 1983. Two years later, as the most prominent U.S. attorney in the country, Giuliani would announce a blockbuster indictment targeting “The Commission,” a ruling committee made up of Mafia brass that adjudicated disputes among the five families.

“There were an awful lot of people, including people in law enforcement, who thought it was totally unrealistic, ridiculous, could not be done,” Giuliani said during a 1987 press conference, recounting the case where he secured eight convictions.

Giuliani’s novel approach to tackling corruption in organized labor and decimating mob leadership earned him celebrity status in the five boroughs and beyond. At the time, these problems seemed intractable.

“Context is important,” said one former staffer in Giuliani’s City Hall, who was granted anonymity to speak about a former boss. “Back when he did this, the Mafia was arguably at the apex of its power — it’s not like today.”

As a prosecutor, Giuliani was adept at getting press. At one point, he was holding several media briefings a week. He perp-walked Wall Street suspects before gaggles of news photographers, even when cases were built on a brittle legal framework. And in 1986, he posed for a photo himself alongside Sen. Alfonse D’Amato. The two were wearing sunglasses and purportedly in disguise as drug addicts. While wearing a leather vest, Giuliani purchased two vials of cocaine for $20.

For de Blasio and the former staffer, these episodes showed Giuliani’’s penchant for innovation began to hew closer to self-promotion as he grew closer to announcing his 1989 mayoral campaign — and has remained there since.

“That same creativity and entrepreneurship led him down a very dangerous path, which was the perp walks and the marrying of his job with his self-obsession and political ambition,” de Blasio said, calling Giuliani’s indictment Monday “more than Shakespearean.”

Ted Goodman, a Giuliani adviser, disputed de Blasio’s characterization and said Giuliani’s record stands for itself.

“Mayor Rudy Giuliani is the most consequential U.S. Attorney in American History,” he said in a statement, noting in that Giuliani actually tried a case involving city corruption himself. “Many know about his record taking down the Mafia and handling the biggest cases on Wall Street, but he also deported Nazis, cleaned up the corrupt Teamsters Union, chased the mob out of Las Vegas and locked up corrupt public officials of both major political parties, including to members of Congress.”

Once Giuliani announced his 1989 run for office — he secured both the Liberal and Republican lines — he unsurprisingly made his prosecutorial experience a central pillar of his campaign, a strategy that helped bring him within 3 points of Dinkins during the November general election.

“The ‘Godfather’ guys from when he was a prosecutor and the bankers he rooted out for a variety of financial crimes: He talked about all those things,” Norman Steisel, a Dinkins deputy mayor, said in an interview.

The race was so close that Giuliani tried again in 1993 in a contest defined by the city’s high crime along with a racially divisive riot in Crown Heights and the ensuing tensions between the Jewish and Black communities. A year before the election, Giuliani spoke at a heated rally of thousands of angry police officers who surrounded City Hall and blocked the Brooklyn Bridge — some of them destroying property and using racist language and imagery toward the city’s first Black mayor, David Dinkins.

By the time Giuliani took the podium for his inauguration speech in early 1994, he had a wide-ranging political platform to draw from that included promises to rein in budget deficits, support education and boost cultural institutions, even as he highlighted the diversity of New York. Reducing crime continued to be a central theme.

“I’ll place a much greater emphasis on stricter enforcement of the law to reverse the growing trend of ever-increasing tolerance for lawless behavior,” Giuliani said days after his term began.

His eight years leading the largest city in the nation — and his actions in the aftermath of 9/11 — cemented Giuliani as a national Republican figure who oversaw a reduction in crime and supported abortion rights and civil unions between LGBTQ partners. The combination of GOP bona-fides with more socially liberal positions, he argued, made him the ideal candidate to take on Democrats during his unsuccessful 2007 bid for president.

By 2018, however, Giuliani had made a marked shift by joining Trump’s legal team and cementing his position in the party’s MAGA wing.

Goodman said that the Giuliani of today is the same person who rose to popularity after fighting crime and comforting the nation after 9/11.

“Few Americans have improved the lives of more people than America’s Mayor, Rudolph W. Giuliani,” he said in a statement. “And remember, that’s a nickname bestowed upon him by Oprah Winfrey herself.”

But Giuliani’s current circumstances are where the new RICO case comes in.

Fulton County District Attorney Fani Willis is now using Giuliani’s novel legal strategy against him. On Monday, she announced an indictment accusing Trump and 18 others, including Giuliani, of trying to reverse Georgia’s electoral votes for President Joe Biden.

“The indictment alleges that, rather than abide by Georgia’s legal process for election challenges, the defendants engaged in a criminal racketeering enterprise to overturn Georgia’s presidential election result,” she said during a press briefing.

Speaking earlier this week, Giuliani blasted Willis’ use of the RICO statutes.

“This is not meant for election disputes,” he said during an appearance on Newsmax. “This is ridiculous what she’s doing.”

But stretching the bounds of the RICO laws, the former City Hall staffer noted, is exactly what Giuliani did when he used it to go after a white-collar financial firm.

“You have to admit, if she is successful and convicts Trump, you’re going to be talking Gov. Willis, Vice President Willis — you are talking about someone who is going to be a superstar,” the staffer said, noting Giuliani’s own meteoric political rise from the courtroom. “I have to tell you something — that is ironic to me.”