Donald Trump’s former attorney Rudy Giuliani is a target of the criminal investigation in Georgia that has been examining efforts to overturn the results of the 2020 election in that state by the former president and his allies, a source briefed on the matter confirmed on Monday.

The move to designate Giuliani, 78, as a target – as opposed to a subject – raises the legal stakes for the ex-New York mayor, identified as a key figure in the attempt to reverse the former president’s electoral defeat to Joe Biden in the state.

The office of Fani Willis, the Fulton county district attorney prosecuting the case, told Giuliani he was a target of the criminal investigation into that attempt.

Willis has already told about a dozen others they are targets, including two state senators and the head of the state Republican party.

The disclosure, earlier reported by the New York Times, presents Giuliani with difficult choices, including whether to invoke his fifth amendment right against self-incrimination in a deposition or cooperate in the hope of earning leniency at sentencing.

Giuliani is scheduled to testify before the special grand jury on Monday in Atlanta. The news of his target designation comes days after a Fulton county judge told prosecutors to indicate to Giuliani whether he was a target or a subject of the criminal investigation.

The Fulton county judge said informing Giuliani about his status would give some clarity on “what impact that has on the extent of his time in front of the grand jury”, given he is scheduled to appear after having taken a long road trip from New York, where he lives.