"As we pieced together the early years of his biography, it seemed as if during the early part of his career he had connections to a lot of Italian mafia figures, and then gradually during the 90s became associated with Russian mafia figures," Simpson said at one point, under oath, about the 45th president of the United States.
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At another point, he was asked by a Republican, Tom Rooney of Florida, whether he could "conclusively say as fact that the Russian government and the Trump campaign were colluding with each other to beat Hillary Clinton."
Simpson replied, "I think that the evidence that has developed over the last year, since President Trump took office, is that there is a well-established pattern of surreptitious contacts ... that supports the broad allegation of some sort of an undisclosed political or financial relationship between the Trump Organization and people in Russia."
However, Simpson said, he was not prepared to say whether that added up to a "criminal conspiracy."
Simpson's research firm, Fusion GPS, had been hired to get information on Trump during the primaries by a Republican media firm, Washington Free Beacon. When Trump became the Republican nominee, the Clinton Campaign and the Democratic Party began picking up the tab for the Fusion research. Simpson hired his friend Christopher Steele, a former British intelligence operative and Russia expert, to gather information from his sources in Russia.
That part of the story is well known by now: Steele's sources told him the Russian government was working with Trump to try to help him beat Clinton, including providing hacked emails. That unproven allegation is among those being investigated by Special Counsel Robert Mueller.
But Simpson also delves into some of his own research on Trump's business dealings, allegations familiar to reporters but not the general public. For example, Simpson testified that he believes Trump's golf courses in Scotland and Ireland may have been financed with illicit Russian money, something media organizations investigated — but reached no conclusion about — during the campaign.
President Trump's son Eric told golf reporter James Dodson in 2014 that the family's company got much of its funding to build its golf courses from Russia, according to an interview Dodson gave last year to Boston public radio station WBUR. But Eric Trump then went on Twitter and denied saying that.
Simpson said he poured over the financial statements of the golf courses.
"And they don't, on their face, show Russian involvement, but what they do show is enormous amounts of capital flowing into these projects from unknown sources and — or at least on paper it says it's from the Trump Organization, but it's hundreds of millions of dollars."
He added, "And these golf courses are just, you know, they're sinks. They don't actually make any money. So, you know, if you're familiar with Donald Trump's finances and the litigation over whether he's really a billionaire, you know, there's good reason to believe he doesn't have enough money to do this and that he would have had to have outside financial support for these things."
Rooney later commented on that as an example of where the evidence wasn't persuasive. But he seemed to acknowledge it was a question whose answer was worth knowing.
"That's exactly my point, is that if we knew that Donald Trump was working with the Russian mafia to fund Doonbeg in Ireland, then there's no way he would be President," Rooney said, according to the transcript. "So, I mean, that's why it's so fascinating."
California's Rep. Adam Schiff, the committee's ranking Democrat, asked, "If the Russians were laundering money through Trump golf courses or Trump condos, would the Russian government be aware of this? Would they be either knowing or active participants potentially in this?"
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Simpson replied, "The Russian mafia is essentially under the dominion of the Russian government and Russian intelligence services .... And so basically everyone in Russia works for Putin now."
His team also observed patterns in real estate dealings involving Trump properties — purchases by unknown entities that were quickly re-sold for a loss — that "were suggestive of money laundering."
He singled out projects in Panama and Toronto where Russian mafia figures were listed as buyers, which he said "smacks of fraud."
"Those both got a lot of fraud associated with them, a lot of fraud allegations, a lot of activity that I would say smacks of fraud, and a lot of Russian mafia figures listed as buyers who may or may not have actually put money into it," Simpson said.
Simpson said at first it seemed to him that Trump's own lawyers would step in to prevent Trump from pursuing real estate deals in Russia, on the basis that transactions could trigger the Foreign Corrupt Practices Act.
"What I later came to believe was that he was, in fact, developing different kinds of business relationships with the Russians," he told the committee. "He'd found other ways to profit from his relationship with that."
Simpson described in detail why he began relaying his findings to reporters in the fall of 2016, just before the November election. Steele had gone to the FBI in July with his findings, but he didn't perceive that the bureau was doing very much.
Simpson said he was shocked and angry when FBI Director James Comey said publicly he was reopening the Clinton email investigation in October 2016, just weeks before the presidential election.
"I was sitting on this piece of knowledge, which was that, in fact, the FBI was investigating the Trump organization for possibly having illegal dealings with the Government of Russia," Simpson said. "We decided that if James Corney wasn't going to tell people about this investigation that, you know, he had violated the rules, and we would only be fair if the world knew that both candidates were under FBI investigation."
Simpson declined to discuss his dealings with the media, but at least one reporter, David Corn of Mother Jones, wrote a storybefore the election after meeting with Steele.
Simpson also asserted that the Russian government had "infiltrated " the National Rifle Association, which spent more than $400 million in the 2016 election, according to public records. The NRA supports mainly Republicans.
"It appears the Russians, you know, infiltrated the NRA, and there is more than one explanation for why," he said in the testimony. "But I would say broadly speaking, it appears that the Russian operation was designed to infiltrate conservative organizations. And they targeted various conservative organizations, religious and otherwise, and they seem to have made a very concerted effort to get in with the NRA. And so there is a Russian banker-slash-Duma member-slash-Mafia leader named Alexander Torshin who is a life member of the NRA. And we spent a lot of time investigating Mr. Torshin. And he is well known to Spanish law enforcement for money laundering activity..."
NBC News has previously reported that Torshin sought a meeting with Trump, and ended up at an an NRA dinner with Donald Trump Jr.
Simpson also mentioned a Russian NRA member named Maria Butina, who he says "started hanging around the Trump transition after the election."
"The most absurd [thing] about this is that, you know, Vladimir Putin is not in favor of universal gun ownership for Russians," said Simpson. "And so it's all a big charade, basically."
An NRA spokesman did not immediately respond to a request for comment. Efforts to reach Torshin and Butina were unsuccessful.
In response to Republican questioning, Simpson also defended the credibility of Steele's dossier, saying much of it has been verified. He also went further to present the committee with new information that hadn't been included in the original dossier.
"I haven't seen anything that has contradicted anything in the memos to date," he said in the November interview. ""Chris [Steele] was a reliable provider of information that turned out to be reliable. ... He was a Boy Scout."