Prosecutors in Atlanta on Monday told lawyers for Rudy Giuliani that he’s a target of their criminal investigation into possible illegal attempts by then-President Donald Trump and others to interfere in the 2020 general election in Georgia.

Special prosecutor Nathan Wade alerted Giuliani’s local attorney in Atlanta that the former New York City mayor could face criminal charges, another Giuliani attorney, Robert Costello, said. News of the disclosure was first reported by The New York Times.

The revelation that Giuliani, a lawyer for Trump, is a target of the investigation by Fulton County District Attorney Fani Willis edges the probe closer to the former president. Willis has said she is considering calling Trump himself to testify before the special grand jury, and the former president has hired a criminal defense attorney in Atlanta.

Law enforcement scrutiny of Trump’s actions is escalating. Last week, the FBI searched his Florida home as part of an investigation into whether he took classified records from the White House to Mar-a-Lago. He is also facing a civil investigation in New York over allegations that his company, the Trump Organization, misled banks and tax authorities about the value of his assets. And the Justice Department is investigating the Jan. 6 insurrection at the U.S. Capitol by Trump supporters and efforts to overturn the election he falsely claimed was stolen.

Giuliani, who spread false claims of election fraud in Atlanta’s Fulton County as he led efforts to overturn the state’s election results, is to testify Wednesday before a special grand jury that was impaneled at Willis’s request.

Also Monday, a federal judge said U.S. Sen. Lindsey Graham must testify before the special grand jury. Prosecutors have said they want to ask Graham about phone calls they say he made to Georgia Secretary of State Brad Raffensperger and his staff in the weeks following the election.

Willis’s investigation was spurred by a phone call between Trump and Raffensperger. During that January 2021 conversation, Trump suggested that Raffensperger “find” the votes needed to reverse his narrow loss in the state.

Willis last month filed petitions seeking to compel testimony from seven Trump associates and advisers.

In seeking Giuliani’s testimony, Willis identified him as both a personal attorney for Trump and a lead attorney for his campaign. She wrote that he and others appeared at a state Senate committee meeting and presented a video that Giuliani said showed election workers producing “suitcases” of unlawful ballots from unknown sources, outside the view of election poll watchers.

Within 24 hours of that Dec. 3, 2020, hearing, Raffensperger’s office had debunked the video. But Giuliani continued to make statements to the public and in subsequent legislative hearings claiming widespread voter fraud using the debunked video, Willis wrote.

Evidence shows that Giuliani’s hearing appearance and testimony were “part of a multi-state, coordinated plan by the Trump Campaign to influence the results of the November 2020 election in Georgia and elsewhere,” her petition says.

Two of the election workers seen in the video, Ruby Freeman and Wandrea “Shaye” Moss, said they faced relentless harassment online and in person after it was shown at a Dec. 3 Georgia legislative hearing where Giuliani appeared. At another hearing a week later, Giuliani said the footage showed the women “surreptitiously passing around USB ports as if they are vials of heroin or cocaine.” They actually were passing a piece of candy.

Willis also wrote in a petition seeking the testimony of attorney Kenneth Chesebro that he worked with Giuliani to coordinate and carry out a plan to have Georgia Republicans serve as fake electors. Those 16 people signed a certificate declaring falsely that Trump had won the 2020 presidential election and declaring themselves the state’s “duly elected and qualified” electors even though Joe Biden had won the state and a slate of Democratic electors was certified.

All 16 of those fake electors have received letters saying they are targets of the investigation, Willis said in a court filing last month.

Attorneys for Graham, R-S.C., have argued that his position as a U.S. senator provides him immunity from having to appear before the investigative panel. But U.S. District Judge Leigh Martin May wrote in an order Monday that immunities related to his role as a senator do not protect him from having to testify. Graham’s subpoena instructs him to appear before the special grand jury on Aug. 23, but his office said Monday he plans to appeal.

Graham had argued that a provision of the Constitution provides absolute protection against a senator being questioned about legislative acts. But the judge found there are “considerable areas of potential grand jury inquiry” that fall outside that provision’s scope. The judge also rejected Graham’s argument that the principle of “sovereign immunity” protects a senator from being summoned by a state prosecutor.

Graham also argued that Willis, a Democrat, had not demonstrated extraordinary circumstances necessary to compel testimony from a high-ranking official. But the judge disagreed, finding that Willis had shown “extraordinary circumstances and a special need” for Graham’s testimony on issues related to an alleged attempt to influence or disrupt the election in Georgia.

May, the judge, last month rejected a similar attempt by U.S. Rep. Jody Hice, R-Ga., to avoid testifying before the special grand jury.

Graham’s office said in a statement Monday that the senator disagrees with the judge’s interpretation of the provision of the Constitution he believes protects him from being questioned by a state official. His lawyers have said he was making inquiries that were part of his legislative duties, related to certification of the vote and to a proposal of election-related legislation.

But the judge wrote that that ignores “the fact that individuals on the calls have publicly suggested that Senator Graham was not simply engaged in legislative factfinding but was instead suggesting or implying that Georgia election officials change their processes or otherwise potentially alter the state’s results.”

In calls made shortly after the 2020 general election, Graham “questioned Raffensperger and his staff about reexamining certain absentee ballots cast in Georgia in order to explore the possibility of a more favorable outcome for former President Donald Trump,” Willis wrote in a petition.

Graham also “made reference to allegations of widespread voter fraud in the November 2020 election in Georgia, consistent with public statements made by known affiliates of the Trump Campaign,” she wrote.

Republican and Democratic state election officials across the country, courts and even Trump’s attorney general have found there was no evidence of voter fraud sufficient to affect the outcome of his 2020 presidential election loss.

Trump-allied lawmakers were planning to challenge the tallies from several battleground states when Congress convened on Jan. 6, 2021, to certify the results under the Electoral Count Act, but after the Capitol attack that day Georgia’s tally was never contested.

Trump has denied any wrongdoing and has described his call to Raffensperger as “perfect.”

Additional reporting by The Associated Press.