The FBI reportedly learned in 2019 that Russia was using Rudy Giuliani as a tool to spread election disinformation

• The FBI reportedly learned that Russia was using Rudy Giuliani to spread disinformation before the 2020 election.
• US officials warned the White House in 2019 about Giuliani's vulnerability to Russian intel, but Trump shrugged it off.
• He's now the target of a federal criminal investigation into whether he violated lobbying laws.

Editor's note: A previous version of this article stated, based on The Washington Post's reporting, that the FBI warned Giuliani that he was the target of a Russian influence operation. The Post has since retracted that detail, and Insider has updated this story accordingly.

The FBI became aware in late 2019 that the Russian government was using former New York mayor Rudy Giuliani as a tool to spread disinformation about the Biden family ahead of the 2020 election, The Washington Post reported.

In the months leading up to the election Giuliani was a fixture on conservative airwaves, where he repeatedly amplified bogus conspiracy theories accusing the candidate Joe Biden and his son Hunter of having corrupt ties to Ukraine. He also pushed the lie that Ukraine and not Russia interfered in the 2016 election, a talking point that can be traced back to Russian President Vladimir Putin.

The Post reported that the FBI learned that the far-right network One America News was also a target of the Russian disinformation campaign.

Giuliani serves as former President Donald Trump's personal attorney, and his actions were said to be so alarming to US officials that they warned the White House and Trump after Giuliani traveled to Kyiv in December 2019 that Russia was using him to funnel disinformation to US audiences before the 2020 election.

Four former officials familiar with the matter told The Post the warnings to the White House were based on several sources, including intercepted communications. The intercepts are said to have shown that during the Ukraine trip Giuliani communicated with people who had ties to Russian intelligence.

He made the trip as part of his effort to dig up dirt related to Hunter Biden's work for the Ukrainian natural-gas company Burisma Holdings. One of the people he met with was the Ukrainian politician Andriy Derkach. The US government has since sanctioned Derkach and described him as an "active Russian agent."

The Post reported that the intercepted communications raised red flags with US officials who worried that Russian officials were using Giuliani as a conduit to feed disinformation to Trump. After the White House was warned about the possibility, the report said, then national security advisor Robert O'Brien told the president to approach any information Giuliani gave him with caution.

Trump shrugged off the warnings, according to The Post. On Wednesday, the FBI raided Giuliani's apartment and office in Manhattan and seized his electronic devices as well as a computer belonging to his personal assistant, Jo Ann Zafonte. Zafonte was served with a grand-jury subpoena, and The New York Times reported that the feds also raided the Washington, DC, home of one of Giuliani's associates and a fellow attorney, Victoria Toensing.

The raids mark an aggressive new phase in a long-running criminal investigation into whether Giuliani broke foreign-lobbying laws through his dealings with Ukraine. The Times later reported that at least one of the search warrants sought evidence about the abrupt firing of Marie Yovanovitch as the US ambassador to Ukraine.

Specifically, prosecutors are said to be examining whether Giuliani was working on behalf of the Ukrainian prosecutor general Yuriy Lutsenko while pushing for Yovanovitch's dismissal.

Yovanovitch appeared for a nine-hour, closed-door deposition on Capitol Hill related to the first impeachment inquiry into Trump. In her opening statement, she said then-Deputy Secretary of State John Sullivan told her that she "had done nothing wrong" but that there was a "concerted campaign" to remove her.

Giuliani and his lawyer have denied any wrongdoing, and his attorney described the FBI's raids as "legal thuggery." The former New York mayor also a statement saying he was targeted because of a "corrupt double standard" and alleging that investigators were ignoring purported illicit activities on the part of Hunter Biden.