Explainer: What's next in the criminal probe of Trump ally Giuliani?

By Jan Wolfe

(Reuters) - Federal agents searched Rudolph Giuliani's Manhattan apartment and office, advancing a criminal investigation into the Ukrainian dealings of Donald Trump's former lawyer.

Here is a summary of what is publicly known about the investigation and what trouble it could spell for Giuliani and the former president:

Why did agents search Giuliani's home and law office?

Giuliani led an effort to dig up dirt on now-President Joe Biden and his son Hunter in Ukraine before the 2020 election and pushed Trump to remove then-U.S. Ambassador to Ukraine Marie Yovanovitch.

Prosecutors are investigating whether Giuliani illegally lobbied the Trump administration on behalf of Ukrainian officials and oligarchs, while also serving as Trump's personal lawyer.

A law passed in 1938, the Foreign Agents Registration Act (FARA), makes it a federal crime to try to influence or lobby the U.S. government on behalf of a foreign official without disclosing it to the Justice Department.

To obtain a warrant, prosecutors first had to persuade a judge that there was "probable cause" to believe that a crime was committed and that the search would turn up evidence of the crime. Agents seized cell phones and computers in Wednesday's search, Giuliani's lawyer said.

The warrants would have required sign-off at the highest levels of the Justice Department, said Lisa Kern Griffin, a law professor at Duke University and former federal prosecutor.

"This development suggests that the investigation into Giuliani’s activities is both ongoing and intensifying," she said.

It is unusual for prosecutors to execute a search warrant on a lawyer's office or home, but federal prosecutors in Manhattan have done so before, most notably in 2018 against Michael Cohen, another former Trump lawyer, who later was sentenced to three years in prison.

Prosecutors clearly think there is real evidence Giuliani broke the law, said Harry Sandick, a former federal prosecutor in Manhattan.

"They had to get approvals from a judge and high levels of the Justice Department," Sandick said. "That is a lot of work to do for a fishing expedition, so I don't think this is one."

What has Giuliani said about the probe?

Giuliani's lawyer Bob Costello suggested the investigation was politically motivated and denied that Giuliani failed to register as a foreign agent.

"Giuliani respects the law, and he can demonstrate that his conduct as a lawyer and a citizen was absolutely legal and ethical," Costello said in a statement.

Costello said the electronics seized were "replete" with information protected by attorney-client privilege, a legal doctrine that generally keeps correspondence between a lawyer and client confidential.

If Giuliani were to be charged, prosecutors would likely argue that attorney-client privilege does not apply, either because Giuliani was not acting as a lawyer, or because his legal advice furthered criminal acts, Sandick said.

"Rudy played a lot of different roles for Trump," Sandick said.

In Cohen's criminal case, a judge said a review of documents seized from Cohen's office turned up only a handful of communications between him and his clients pertaining to actual legal advice.

Could this probe implicate Trump?

Giuliani's dealings in Ukraine were clearly intended to benefit Trump, and former Trump administration officials have said in media interviews and congressional testimony that Giuliani was acting at Trump's direction.

But if the investigation is focused on FARA then Trump is unlikely to be charged as Giuliani's co-conspirator, Sandick said.

If Giuliani failed to comply with FARA's disclosure requirements, it is his own doing, not Trump's, Sandick said.

But it is possible the investigation into Giuliani could expand, particularly if he were to cooperate with prosecutors as Cohen did and implicate Trump in criminal activity, Sandick said.

"This is all very reminiscent of Cohen," Sandick said. "Cohen certainly tried to cooperate, so it's hard for me to say it is impossible."

"The investigation may not have a direct legal impact on Trump, but the fact that the president's lawyer and close adviser could be prosecuted for acting as an agent of a foreign principal is pretty shocking," he said.

Trump on Thursday criticized the investigation and said he had no idea what FBI agents were looking for when they searched his former lawyer’s apartment and office.

"It’s very, very unfair," Trump, told Fox Business Network in an telephone interview. "Rudy is a patriot who loves this country and I don’t know what they’re looking for, what they’re doing."

(Reporting by Jan Wolfe; Editing by Noeleen Walder and Grant McCool)