The Committee voted unanimously Thursday to released the transcript of Simpson's November 14 appearance before the committee, one of three congressional panels investigating Russian actions during the 2016 presidential election campaign.
The 165-page interview transcript is available here.
"We also had sort of more broadly learned that Mr. Trump had longtime associations with Italian organized crime figures", Simpson said.
Simpson said that he based his suspicions on the fact that Trump is a billionaire - as he has claimed to be - and therefore there was "good reason" to believe he doesn't have enough money to fund his Irish and Scottish golf courses and would "have had to have outside financial support for these things".
Mr Simpson said that he is mostly working off public records.
Recently released testimony shows Fusion GPS founder was trying to steer the FBI away from further investigation of the Clintons while he was encouraging investigators to look into Trump.
These matters are now under investigation by the House Permanent Select Committee on Intelligence, the Department of Justice (DOJ) inspector general, and possibly special counsel Robert Mueller.
"I didn't think he was going to be very interesting and very important, partly because he was so young".
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Trump supporters and those closest to the president maintain that the numbers are real and people should get over it. Nasreddine came to Canada as a teenager with his Druze family during the civil war in his homeland, Lebanon.
He said some of Trump's dealings exhibited "the patterns of activity that we thought might be suggestive of money laundering".
Mr Simpson testified that his firm Fusion GPS, which had been hired by Mr Trump's opponents to find damaging material on him during the 2016 campaign, investigated a claim by his son Eric Trump that the Trump Organisation had access to tens of millions of dollars in Russian funding for their golf courses. Other elements of the dossier have been confirmed and supporters of the document say it broadly describes an observable pattern of contacts between Moscow and the Trump campaign. "But in any event, we did look at some Kushner stuff and specifically focused on the project in Jersey City, I think partly because Trump had a position in that project", Simpson said.
"So the first thing that I would do would be to subpoena the brokers and the people, the other people that were involved in the transactions, and the title companies and the.other intermediaries that would have that kind of information", Simpson said, when asked specifically about how the committee should go about the investigating the money laundering allegations.
During his testimony, Simpson urged the committee to continue its investigation into the president.
Fusion GPS, based in Washington, hired former British spy Christopher Steele to investigate Trump's business dealings with Russian Federation.
He said he was not aware of inaccuracies in the work of the ex-spy, Christopher Steele, who was hired for the research and relied on a network of his own sources. In 2016, Steele later handed over his findings included in the dossier to the Federal Bureau of Investigation.
Ever since Feinstein released the testimony on January 9, House Intelligence Committee Democrats have been asking that Simpson's testimony to their committee be made public.