Glenn Simpson, founder of the opposition research firm behind the infamous Trump dossier, testified behind closed doors before Congress on Tuesday.

During his seven-hour grilling, Simpson denied knowing that research he did as part of a pro-Kremlin lobbying campaign would end up in the hands of Yuri Chaika, Russia’s prosecutor general. He expressed his regret, according to a report in The Daily Caller.

A source familiar with Glenn Simpson’s testimony told The Daily Caller that Simpson also told the House Permanent Select Committee on Intelligence (HPSCI) that he was aware that Christopher Steele, the British spy who wrote the dossier, had provided briefings to FBI officials during the campaign.

At the same time Fusion GPS was being paid by the Clinton campaign and DNC for the Trump investigation, Simpson’s firm was also working for a law firm that was representing Prevezon Holdings, a Russian energy company that faced stiff penalties from the Magnitsky Act.

Fusion’s task was to investigate Bill Browder, the London-based banker behind the Magnitsky Act, a 2012 law that sanctions Russian criminals for killing Russian lawyer Sergei Magnitsky to cover up the theft of $230 million from the Russian treasury.

Magnitsky was Browder’s former lawyer. He had been hired by Browder to investigate a massive Russian money laundering scheme.

Simpson reportedly worked closely with Natalia Veselnitskaya, the Russian lawyer who attended the infamous June 9, 2016 meeting with Donald Trump Jr. at Trump Tower, on the Browder project. In their efforts to mislead the Trump team, Veselnitskaya took a four-page memo on Browder to the Trump Tower meeting.

Veselnitskaya recently acknowledged in an interview with NBC News that in Oct. 2015, she took research that Simpson compiled on Browder to Chaika, a close ally of Vladimir Putin’s. She also admitted to consulting for the Russian attorney general. In May 2016, Chaika called on the U.S. government to help Russia in its efforts to detain Browder.

In his testimony to Congress, Browder explained how Fusion GPS, Veselnitskaya, and Chaika have attempted to smear him in their efforts to undercut the Magnitsky Act.

He accused Simpson of having aided and abetted the Russian government in its attempt to imprison him — and likely kill him.

“If it is true that Glenn Simpson was supplying information about me to the Russian government, it’s far more serious than smear campaigning or Foreign Agents Registration Act violations,” Browder told The DC last week, after it was revealed that Simpson’s research ended up on Chaika’s desk.

For more information on the Magnitsky Act and how it leads directly to Veselnitskaya’s efforts on behalf of the corrupt Russian leader, Vladimir Putin, check out this copy of the prepared remarks Browder submitted to the Senate Judiciary Committee in July prior to a hearing about Foreign Agents Registration Act enforcement. The committee also called as witnesses former Trump campaign chairman Paul Manafort, Donald Trump Jr., and Simpson.

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