A lawyer who for years represented Rudy Giuliani in a variety of legal matters sued him on Monday.

Robert Costello and his firm, Davidoff Hutcher & Citron LLP, allege in the suit that the former New York City mayor owes them nearly $1.4 million.

The lawsuit claims Costello and the firm represented Giuliani during criminal investigations by the U.S. Attorney for the Southern District of New York, the Fulton County District Attorney's Office, special counsel Jack Smith and during the U.S. House Jan. 6 committee's investigation.

Costello and the law firm also claim to have been involved with litigation surrounding more than 10 lawsuits filed against Giuliani "in various state and federal courts as well as participating in representing the Defendant in disciplinary proceedings regarding his law license in the District of Columbia" and New York.

Giuliani criticized the suit and Costello, who has been a confidant and supporter of the former mayor for decades, in a statement to CBS News.

"I can't express how personally hurt I am by what Bob Costello has done," Giuliani said. "It's a real shame when lawyers do things like this, and all I will say is that their bill is way in excess to anything approaching legitimate fees."

Told of Giuliani's comment, Costello said in a text message to CBS News, "How can he take a personal affront when he owes my firm $1.4 million? For almost four years he received bills and never complained (and never paid)."

"He only said they were excessive when we told him we would sue. It's too late for that frivolous claim as he will find out in court," Costello said. "I'm sorry he took the low road here because he is feeling desperate."

The lawsuit claims Giuliani has paid $214,000 of a $1,574,196.10 tab accrued since signing a retainer agreement with Costello in 2019. His most recent payment was $10,000 on Sept. 14, according to the suit.

In February, Costello sued Steve Bannon for unpaid legal bills. Bannon, the former White House chief strategist to former President Donald Trump, was ordered by a New York judge in July to pay Costello's firm nearly $500,000.

In March, Costello was briefly the focus of intense scrutiny when attorneys for Trump requested he be called before a grand jury in Manhattan that was closing in on what would become the first ever indictment of a former president. Costello later told CBS News and other outlets that he sought to portray the case's key witness, former Trump attorney Michael Cohen, as a liar on a "revenge tour."

He was with Giuliani in late April for a meeting at Mar-a-Lago, seeking Trump's help with Giuliani's growing financial burden stemming from legal fees.

Costello led Giuliani's effort to obtain local counsel before being interviewed by a special purpose grand jury in Fulton County, Georgia, in 2022, but he was not involved in a similar effort after Giuliani was indicted alongside Trump and 17 others on August 15, he confirmed to CBS News that month.

Giuliani, Trump and their co-defendants have entered not guilty pleas in the case, in which they're accused of running a "criminal enterprise" in their efforts to thwart Georgia's 2020 presidential election results after the state swung for President Joe Biden.

Giuliani and Trump have denied any wrongdoing in the case. 

Trump hosted a $100,000 per plate fundraiser in support of Giuliani on Sept. 7 at his country club in Bedminster, New Jersey. It is unclear how much the event raised for Giuliani personally, but his son, Andrew Giuliani, said on a radio show before the event that he expected to bring in at least $1 million.

Giuliani's New York City apartment is for sale, currently listed by Sotheby's for $6.5 million.

Graham Kates

Graham Kates is an investigative reporter covering criminal justice, privacy issues and information security for CBS News Digital. Contact Graham at [email protected] or [email protected]