• Robert Mueller. Thomson Reuters

  Robert Mueller obtained a search warrant for records of "inauthentic" Facebook accounts

• It's bad news for Russian election interference "deniers"
• Mueller may be looking to charge specific foreign entities with a crime

FBI Special Counsel Robert Mueller reportedly obtained a search warrant for records of the "inauthentic" accounts Facebook shut down earlier this month and the targeted ads these accounts purchased during the 2016 election. 

The warrant was first disclosed by the Wall Street Journal on Friday night and the news was later confirmed by CNN.

Legal experts say the revelation has enormous implications for the trajectory of Mueller's investigation into Russia's election interference, and whether Moscow had any help from President Donald Trump's campaign team.

"This is big news — and potentially bad news for the Russian election interference 'deniers,'" said Asha Rangappa, a former FBI counterintelligence agent.

Rangappa, now an associate dean at Yale Law School, explained that to obtain a search warrant a prosecutor needs to prove to a judge that there is reason to believe a crime has been committed. The prosecutor then has to show that the information being sought will provide evidence of that crime.

Mueller would not have sought a warrant targeting Facebook as a company, Rangappa noted. Rather, he would have been interested in learning more about specific accounts. 

"The key here, though, is that Mueller clearly already has enough information on these accounts — and their link to a potential crime to justify forcing [Facebook] to give up the info," she said. "That means that he has uncovered a great deal of evidence through other avenues of Russian election interference."

It also means that Mueller is no longer looking at Russia's election interference from a strict counterintelligence standpoint — rather, he now believes he may be able to obtain enough evidence to charge specific foreign entities with a crime.

Former federal prosecutor Renato Mariotti, now a partner at Thompson Coburn LLP, said that the revelation Mueller obtained a search warrant for Facebook content "may be the biggest news in the case since the Manafort raid."

The FBI conducted a predawn July raid on the home of Trump's former campaign chairman, Paul Manafort, in late July. The bureau is reportedly investigating Manafort's financial history and overseas business dealings as part of its probe into possible collusion between the campaign and Moscow.

White House senior adviser Jared Kushner listens as President Donald Trump answer questions regarding the ongoing situation in North Korea, Friday, Aug. 11, 2017, at Trump National Golf Club in Bedminster, N.J. Associated Press/Pablo Martinez Monsivais

The Facebook warrant "means that Mueller has concluded that specific foreign individuals committed a crime by making a 'contribution' in connection with an election," Mariotti wrote on Saturday.

"It also means that he has evidence of that crime that convinced a federal magistrate judge of two things: first, that there was good reason to believe that the foreign individual committed the crime. Second, that evidence of the crime existed on Facebook."

That has implications for Trump and his associates, too, Mariotti said. 

"It is a crime to know that a crime is taking place and to help it succeed. That's aiding and abetting. If any Trump associate knew about the foreign contributions that Mueller's search warrant focused on and helped that effort in a tangible way, they could be charged."

Congressional intelligence committees are homing in on the campaign's data operation as a potential trove of incriminating information.

Democratic Rep. Adam Schiff, the ranking member of the House Intelligence Committee, told MSNBC earlier this month that he wants to know how sophisticated the Russian-bought ads were — in terms of their content and targets — to determine whether they had any help from the Trump campaign.

The House Intelligence Committee also wants to interview the digital director for Trump's campaign, Brad Parscale, who worked closely with Trump's son-in-law Jared Kushner.

Kushner was put in charge of the campaign's entire data operation and is now being scrutinized by the FBI over his contacts with Russia's ambassador and the CEO of a sanctioned Russian bank in December.

Facebook said in its initial statement that about 25% of the ads purchased by Russians during the election "were geographically targeted," and many analysts have found it difficult to believe that foreign entities would have had the kind of granular knowledge of American politics necessary to target specific demographics and voting precincts.

In a post-election interview, Kushner told Forbes that he had been keenly interested in Facebook's "micro-targeting" capabilities from early on.

“I called somebody who works for one of the technology companies that I work with, and I had them give me a tutorial on how to use Facebook micro-targeting,” Kushner said.

“We brought in Cambridge Analytica. I called some of my friends from Silicon Valley who were some of the best digital marketers in the world," Kushner said. "

And I asked them how to scale this stuff . . . We basically had to build a $400 million operation with 1,500 people operating in 50 states, in five months to then be taken apart. We started really from scratch," he added.