WASHINGTON (AP) -- One lied about his knowledge of Russian-hacked emails, another about a Russian real estate deal, a third about dialogue over sanctions with a Russian ambassador.
A pattern of deception by advisers to President Donald Trump, aimed at covering up Russia-related contacts during the 2016 campaign and transition period, has unraveled bit by bit in criminal cases brought by special counsel Robert Mueller.
The lies to the FBI and to Congress, including by Trump's former fixer and his national security adviser, have raised new questions about Trump's connections to Russia, revealed key details about the special counsel's findings and painted a portrait of aides eager to protect the president and the administration by concealing communications they presumably recognized as problematic.
The false statements cut to the heart of Mueller's mission to untangle ties between the Trump campaign and Russia and to establish whether they colluded to sway the election. They concern some of the central questions of the investigation, including why the incoming Trump administration discouraged Russia from retaliating over sanctions imposed for election hacking; who knew what when about illegally obtained Democratic emails; and how plans for a Trump Tower in Moscow came together and fell apart.
"I think you can draw a conclusion that these false statements generally relate to an effort to protect the president of the United States in connection with his dealings with Russia," said Washington lawyer Daniel Petalas, a former Justice Department prosecutor. "That's what makes them material to the investigation that Mueller is pursuing, which is a necessary element of a false statement claim — that it has to be material."
The most recent example came Thursday, when Trump's former lawyer, Michael Cohen, pleaded guilty to lying to Congress about negotiations he had on Trump's behalf for a real estate deal in Moscow.
Though he told lawmakers the talks were done by January 2016, he admitted they actually lasted as late as June — after Trump had secured the Republican nomination and after Russians had penetrated Democratic email accounts for communications later released through WikiLeaks. He also said he had briefed Trump about the project's progress and members of his family.
Cohen said he lied out of loyalty to Trump, who insisted throughout the campaign that he had no business dealings in Russia, and to be consistent with his political messaging.
Though the Cohen plea didn't directly connect to Trump's campaign, other cases have.
George Papadopoulos, a former Trump campaign adviser, pleaded guilty to lying to the FBI about April 2016 conversations with a Maltese professor who told him Russians had "dirt" on Hillary Clinton in the form of "thousands of emails." Papadopoulos told the FBI he wasn't part of the campaign when he encountered the professor, Joseph Mifsud, even though he had joined weeks earlier.
His lawyers said Papadopoulos, now serving a 14-day prison sentence, "lied to save his professional aspirations and preserve a perhaps misguided loyalty to his master."
Trump's former national security adviser, Michael Flynn, is being sentenced later this month after admitting lying to the FBI by saying he didn't discuss sanctions against Russia during the transition with Sergey Kislyak, the Russian ambassador to the U.S. at the time.
That deception was flagged for the White House in January 2017 by Obama administration holdover Sally Yates, who as acting attorney general told White House counsel Don McGahn that officials were misleading the public by falsely declaring Flynn hadn't discussed sanctions.
Flynn's guilty plea was especially significant in that it made clear other transition officials were aware of his Kislyak conversations and discussed with him what he would say. And while Flynn was fired in February 2017, his importance to Trump became evident when ex-FBI Director James Comey said Trump had encouraged him during a private meeting that same month to end an investigation into Flynn.
More lies followed as prosecutors this week accused former Trump campaign chairman Paul Manafort of lying even after his guilty plea, though they have not said about what.
And a draft plea agreement against another Trump supporter, conspiracy theorist Jerome Corsi, accused him of misrepresenting a conversation with Trump confidant Roger Stone about WikiLeaks, which published thousands of stolen emails ahead of the election to harm the Clinton campaign.
A false statement charge can be a powerful cudgel for prosecutors, especially in investigations like this one where witnesses are recalcitrant and openly defiant. In the Mueller investigation, perhaps emboldened by Trump's antagonist stance, witnesses have increasingly lashed out against the government's authority. Trump and Stone have publicly attacked Mueller's investigation, while Corsi rejected a plea offer and accused prosecutors of trying to bully him into saying what they want to hear.
"You've got a system where you're trying to take evidence from people, get their testimony under penalty of prosecution if you lie," said Duke University law professor Sam Buell. "And that's what you do when you have uncooperative people (who are) trying to conceal something that you're trying to get to the bottom of."
More false statement charges could be coming. Sen. Richard Burr, chairman of the Senate intelligence committee, said the panel has made referrals to prosecutors and cited Cohen as an example.
"It's a loud message to everybody that is interviewed by our committee, regardless of where that prosecution comes from, if you lie to us, we're going to go after you," Burr said.
Though Trump regularly complains about Mueller's style, there's nothing unusual about prosecutors pursuing false statement charges to send a message and using their lies for cases against higher-level targets.
"This is what happened to the mob, this is what happened to the drug cartels," Buell said.
Not to mention, he noted, past Washington investigations like Watergate.