It is unclear how long the Torshin inquiry has been ongoing, but the news comes as Justice Department special counsel Robert Mueller’s sweeping investigation into Russian meddling in the 2016 election, including whether the Kremlin colluded with Trump’s campaign, has been heating up.

All of the sources spoke on condition of anonymity because Mueller’s investigation is confidential and mostly involves classified information.

A spokesman for Mueller’s office declined to comment.

Disclosure of the Torshin investigation signals a new dimension in the 18-month-old FBI probe of Russia’s interference.

McClatchy reported a year ago that a multi-agency US law enforcement and counter-intelligence investigation into Russia’s intervention initially included a focus on whether the Kremlin secretly helped fund efforts to boost Trump, but little has been said about that possibility in recent months.

The extent to which the FBI has evidence of money flowing from Torshin to the NRA, or of the NRA’s participation in the transfer of funds, could not be learned.

However, the NRA reported spending a record US$55 million on the 2016 elections, including US$30 million to support Trump – triple what the group devoted to backing Republican Mitt Romney in the 2012 presidential race.

Most of that was money was spent by an arm of the NRA that is not required to disclose its donors.

Two people with close connections to the powerful gun lobby said its total election spending actually approached or exceeded US$70 million.

The reporting gap could be explained by the fact that independent groups are not required to reveal how much they spend on internet ads or field operations, including get-out-the-vote efforts.

During the campaign, Trump was an outspoken advocate of the Second Amendment right to bear arms.

Torshin, a leading figure in Putin’s party, was implicated in money laundering by judicial authorities in Spain in 2016.

Spanish investigators alleged in an almost 500-page internal report that Torshin, who was then a senator, capitalised on his government role to assist mobsters laundering funds through Spanish properties and banks.

A summary obtained by McClatchy of the still-secret report links Torshin to Russian money laundering and describes him as a godfather in a major Russian criminal organisation called Taganskaya.

Investigators for three congressional committees probing Russia’s 2016 operations also have shown interest in Torshin, a lifetime NRA member who has attended several of its annual conventions. Torshin spoke to Donald Trump Jnr during a gala event at the group’s national gathering in Kentucky in May 2016, when his father won an earlier-than-usual NRA presidential endorsement.

The NRA did not immediately respond to requests for comment.

Torshin could not be reached for comment, and emails to the Russian central bank seeking comment from Torshin and the bank elicited no response.

Mueller’s investigation has been edging closer to Trump’s inner circle.

This week, The New York Times reported that Mueller had negotiated an agreement under which Steve Bannon, who was recently ousted from his post as a senior White House adviser, would fully respond to questions about the Trump campaign. Bannon headed the campaign over its final weeks.

Since taking over the investigation last May, Mueller has secured guilty pleas from two former Trump aides: former national security adviser Michael Flynn and former campaign foreign policy adviser George Papadopoulos. Both of them agreed to cooperate with prosecutors.

He has also placed criminal charges against two other top campaign figures: former campaign chairman Paul Manafort and his deputy, Rick Gates.

Torshin’s ties with the NRA have flourished in recent years. In late 2015, he hosted two dinners for a high-level NRA delegation during its weeklong visit to Moscow that included meetings with influential Russian government and business figures.

The House and Senate Intelligence committees and Democrats on the Senate Judiciary Committee also have taken an interest in Torshin as part of their parallel inquiries into Russia’s interference in the 2016 elections.

In questioning Trump Jnr at a closed-door hearing in mid-December, investigators for the Senate Intelligence Committee asked about his encounter with Torshin at the NRA convention, according to a source familiar with the hearing.

Alan Futerfas, a lawyer for Trump Jnr, said his client and Torshin talked only briefly when they were introduced during a meal.

“It was all gun-related small talk,” Futerfas told McClatchy.

California Senator Dianne Feinstein, the senior Democrat on the Senate Judiciary Committee, sent letters in November to two senior Trump foreign policy aides, J.D. Gordon and Sam Clovis, seeking copies of any communications they had with or related to Torshin; the NRA; veteran conservative operative Paul Erickson; Maria Butina, a Torshin protégé who ran the Russian pro-gun group he helped launch, and others linked to Torshin.