Felix Sater, the former Port Washington resident and key figure in the Trump investigation, had led a life in the shadows of organized crime and terrorism over 10 years as an FBI informant, according to federal court records and media reports.

“He was a major operator,” State Sen. Todd Kaminsky (D-Long Beach), a former federal prosecutor, told Newsday. Kaminsky had worked on Sater's presentencing report that led to Sater's cooperation with federal officials. “He cooperated for an extraordinary length of time that you almost never see. He provided information that no one else could."

Sater's back story almost sounds like a movie script, according to numerous reports. He’s a Russian immigrant who once did prison time for stabbing someone in a bar with a with a broken margarita glass and later was nabbed in a stock swindling scheme. He wheeled and dealed in Trump Tower trying to forge business deals around the globe and allegedly helped fugitive Kazakhs invest millions of dollars in now-troubled U.S. ventures. And, for more than a decade, he secretly worked as an informant for the FBI, providing intelligence on al-Qaida, North Korea, New York-based mafiosos and Russian organized crime.

“I was building Trump Towers by day and hunting bin Laden by night,” Sater, 52, told the Los Angeles Times in 2017.

Sater's name surfaced again Thursday when Michael D. Cohen, President Donald Trump’s former lawyer, pleaded guilty to lying to Congress about the details of a Russian real estate deal he negotiated on Trump’s behalf.

As part of his statement, Cohen said he worked with an individual whom news reports identified as Sater on a Trump-branded Moscow project amid the 2016 presidential campaign; the deal fell apart, though, in early 2016.

Sater’s history with the Trumps and Russia make him part of the probe by special prosecutor Robert Mueller.

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According to media reports and interviews Sater has given, he was part of several attempts by Trump to garner business deals in Russia, starting with a 2005 effort to build a “Trump Tower” in Moscow. In 2006, he accompanied Donald Trump Jr. and Ivanka Trump around the city to meet with potential business partners.

But later, Bayrock — Sater’s company, which was headquartered in Trump Tower in Manhattan — partnered with the Trump Organization to build properties in New York and Florida, financed with Russian and Kazakhstan money, according to lawsuits alleging embezzlement and fraud involving top Kazakhstan bankers who were investing in Europe and the United States.

And in February 2017, Sater said he met with Cohen to deliver a Russia-Ukraine peace settlement proposed by a pro-Russia Ukrainian lawmaker.

“What could be wrong in helping stop a war and trying to achieve peace?” he told Fox News after The New York Times broke the story about the proposal. He moved to California from Long Island last February, according to media reports. Calls to a phone number once associated with Sater went unanswered Thursday.

Amid all the deal brokering — and while he was working in Trump Tower — Sater also was acting as a confidential informant for federal officials.

Kaminsky also once vouched for his value as a source.

In a 2011 secret proceeding, Kaminsky filed a document disclosing that Sater had turned government witness after pleading guilty in 1998 to stock fraud. For more than a decade Sater provided sufficient information to help convict 20 individuals, including “members of La Cosa Nostra," some of whom were in the Gambino, Genovese and Bonanno crime families.

Further, Sater provided information about Afghan missile sales and identifying details about al-Qaida members. That’s largely why Sater received only a small fine for the 1998 stock fraud conviction, according to the document, which was filed in federal court.

Sater’s “cooperation was extraordinary both in terms of its depth and breadth,” Kaminsky wrote in the presentencing report. “It is rare to find a cooperator who provides information about organizations as varied as the ones here.”

In November 2015, while Trump was a presidential candidate, Sater sent Cohen the email that has become part of the Mueller probe. He said he might be able to finally line up the deal for a Moscow Trump Tower and suggested he could get Russian President Vladimir Putin to say “great things” about Trump. In the process, it all might help get Trump elected, Sater said in the email.

But earlier this year, Sater told BuzzFeed News he was just pumping a potential deal. He said he had nothing to do with any Russian involvement in the 2016 election.

“If I could get a deal done and I could make money and he (Trump) could look like a statesman, what … is the downside, right,” Sater said.