Mueller's team is questioning Russian oligarchs over whether they illegally funneled money into Trump's campaign or inauguration

AP

Robert Mueller.

• The special counsel Robert Mueller's team is questioning Russian oligarchs as it investigates whether Russian money was illegally funneled into President Donald Trump's campaign or inauguration.
• Mueller is also investigating whether wealthy Russians used Americans or American companies as conduits to funnel money to the US in support of Trump.
• At least one US organization has drawn scrutiny over whether a wealthy Russian banker used it to channel money to the Trump campaign.
• At least six Putin-allied Russians attended Trump's inauguration - one of whom had two American associates who donated over $1 million to Trump's inaugural committee.

Investigators working for the special counsel Robert Mueller are questioning several Russian oligarchs - at times after stopping them at the airport when they travel to the US - in connection to the Russia investigation, CNN reported Wednesday.

In particular, prosecutors are said to be focused on whether wealthy Russians illegally funneled money, either directly or indirectly, into President Donald Trump's campaign or inauguration.

At least one wealthy Russian was stopped and searched after his private jet landed in New York, and another was also stopped during a recent trip to the US, according to CNN.

The special counsel's team has also reportedly requested documents and an interview with a third Russian oligarch who has not recently traveled to the US. Sources did not divulge the names of the oligarchs who have been questioned to CNN.

Campaign finance laws prohibit foreign nationals from donating to US political campaigns, and Mueller has been interested in the flow of Russian money into the 2016 election since at least September.

ABC News reported at the time that Mueller had asked witnesses about donations to the campaign from US citizens with ties to Russia. Investigators are also said to be interested in whether wealthy Russians used American donors or American companies with their own political action committees to indirectly infuse money into the election.

At least one prominent US organization has drawn scrutiny for its ties to wealthy Russians and faced questions over whether it may have been used as a vessel to funnel money into Trump's campaign.

Earlier this year, it emerged that the FBI is investigating whether Alexander Torshin, a prominent Russian banker and politician with close ties to Russian President Vladimir Putin, used the National Rifle Association to illegally send money to the Trump campaign. The NRA said it spent a record $55 million on the election, most of which came from a sector of the organization that isn't required to disclose its donors.

The NRA has emphasized, and media reports have confirmed, that Torshin, not the organization, is under FBI investigation.

Torshin attended the NRA's convention every year between 2012 and 2016, occasionally with longtime assistant and fellow gun-rights activist Maria Butina at his side. He has met every NRA president since 2012, according to NPR. When the NRA sent a delegation to Moscow in the winter of 2015, it was Torshin who received them on behalf of The Right to Bear Arms, a Russian gun-rights group which is seen as the NRA's counterpart.

Butina has been cultivating her own ties with American gun-rights activists, like Republican strategist Paul Erickson, with whom she has been acquainted since at least 2013.

Erickson invited scrutiny last year, when it was reported that he tried to arrange a backdoor meeting between Trump and Putin, with Torshin acting as "President Putin's emissary on this front." Butina made a similar request to the Trump campaign through another right-wing advocate. Neither Trump nor his campaign are known to have entertained the request. Donald Trump Jr. and Torshin did, however, attend a separate NRA dinner the same night.

At least 6 Putin-allied Russians attended Trump's inauguration

Yury Martyanov/AP

Natalia Veselnitskaya, who met with Donald Trump Jr. in June 2016, is best known in the US for defending a Russian businessman accused by the US government of laundering millions.

Butina was later one of six Putin-allied Russians who attended Trump's inauguration in January 2017. Natalia Veselnitskaya and Rinat Akhmetshin, the two Russian lobbyists who met with top Trump campaign officials in June 2016 offering dirt on Democratic nominee Hillary Clinton, was also there.

Wealthy Russian pharmaceutical executive Alexey Repik and his wife were there, as was energy tycoon Viktor Vekselberg. Vekselberg is said to be closely aligned with Putin, with whom he frequently meets to discuss business.

According to federal filings reviewed by The Washington Post, two of Vekselberg's American associates donated a combined $1.25 million to Trump's inaugural committee.

Mueller is tasked with investigating Russia's interference in the 2016 US election, and his focus on the flow of Russian money into the election is indicative of the wide-ranging nature of the investigation. Among other things, it shows that the special counsel is not just interested in whether Americans committed any crimes in connection to the election, but whether Russian nationals were involved as well.

In February, Mueller's office indicted 13 Russian nationals and three Russian entities for conspiring to meddle in the election by mounting a social-media influence operation meant to sway voters in Trump's favor. Last month, it was reported that prosecutors are homing in on the hack of the Democratic National Committee and subsequent dissemination of stolen emails in the run-up to the November 2016 election. The US intelligence community concluded that the breach was carried out by Russia-linked actors on orders from the Kremlin.

In addition to investigating whether any Americans - including Trump - had prior knowledge of the hacks, Mueller's team is also reportedly scoping out the Russian operatives who were involved.