WASHINGTON — In July, Rudy Giuliani was desperate for more information about Hunter Biden's work in Ukraine.

So he turned to his longtime go-between for Ukrainian deals, a 44-year-old New York-based businessman named Vitaly Pruss.

According to Pruss, Giuliani asked him to call Pruss' close friend, the owner of Burisma, the Ukrainian natural gas company that formerly had Hunter Biden on its board. Giuliani wanted to know if the owner, Mykola Zlochevsky, would meet with him to talk about Biden.

But Zlochevsky made it clear "he wanted nothing to do with it," Pruss told NBC News in an interview at a restaurant in midtown Manhattan.

Among the unresolved mysteries in the impeachment saga is how Giuliani, the president's lawyer and a man with little known background in foreign policy, became the White House's point man on Ukraine. The answer in part lies with his relationship with Pruss, who has acted as the former New York mayor's political and business matchmaker in the former Soviet Union for years.

Few people have crossed paths with as many central characters in the Ukraine impeachment saga as Pruss.

He met Energy Secretary Rick Perry on a trip to Israel in 2010. On flights back and forth to Kyiv, he struck up an acquaintance with America's top diplomat in Ukraine, Bill Taylor. At investment conferences, he has met the former U.S. ambassador Marie Yovanovitch, who was ousted from her post in Kyiv in May, partly through Giuliani's efforts. And Pruss knows most of the Ukrainian political players.

The website for Pruss' company, TriGlobal Strategic Ventures, is a veritable slideshow of Giuliani's connections in Ukraine in recent years, with pictures of him smiling with local officials. And almost all of the relationships laid out in the website's photos are links that House Democrats now want to know more about.

The Democratic lawmakers are demanding to see all of Giuliani's communications, contracts and documents related to Pruss, as part of their impeachment inquiry. Giuliani has refused to cooperate with the congressional investigation.

His lawyer said Giuliani believes the congressional subpoena is "overbroad, unduly burdensome, and seeks documents beyond the scope of legitimate inquiry."

Shortly after Democrats subpoenaed Giuliani, Pruss' company took down its website without explanation. Pruss said the timing was a coincidence and was merely for website "maintenance." It's now back up.

Pruss played down his Forrest Gump-like role in the impeachment drama and said he is befuddled that his name cropped up in impeachment subpoenas. He said that despite his relationship with Giuliani, he had nothing to do with the events that form the basis of the impeachment inquiry into whether President Donald Trump withheld military aid to Ukraine for his own personal political gain.

"I have no idea why in the world I'm in there."

Giuliani is now under investigation by federal prosecutors in New York, and Pruss could have crucial insights about how the former mayor carries out his lobbying for foreign clients.

Vitaly Pruss, Rudy Giuliani's go-between in the former Soviet Union, in an undated picture. via Facebook

A relationship dating back to 2003

Born in Belarus, Pruss registered his business to a Passaic, New Jersey, address in 2005, according to public records. He first focused on the "introduction business" where he matched high-level Western officials with companies willing to pay them for appearing at public and private events. He's a U.S. citizen and New York resident but travels constantly. In the last 30 days alone, he's been in Israel, Vienna, Kyiv and Kazakhstan.

He said the bulk of his work today is in drumming up investments in American nursing homes from Ukraine, Russia and Kazakhstan.

Pruss' bio claims he has "successfully created and developed strategies" for companies like the Russian state oil and gas pipeline monopoly, TransNeft, which was sanctioned by the U.S. government in 2014 after the Russian invasion of Crimea. When asked about his dealings with TransNeft, he said he only presented the company with a proposal and it was long before sanctions were imposed.

Pruss said his relationship with Giuliani started back in 2003 when he was looking for a big Western name to address the board of Magnitogorsk Iron and Steel Works, one of the largest steel companies in Russia.

At the time Giuliani, who became internationally famous after the 9/11 attack on New York, was commanding $100,000 per speech through the Washington Speaker's Bureau. His speeches earned him an estimated $8 million a year, according to his divorce filings at the time.

Pruss said he made a request through the speaker's bureau and negotiated a payment for the appearance. Then he said he went with Giuliani on the trip, flying with him first to Moscow and then on to the Ural Mountains for the meeting.

He said at that point he and the former mayor hit it off, and through the years he has found Giuliani to be widely "loved and respected."

On his website, there are photos in May 2008 and April 2015 showing Giuliani with Vitaly Klitschko, the ex-boxer who is now mayor of Kyiv, on his visits to New York City. Pruss said he made that connection. House lawmakers leading the impeachment inquiry have raised questions about "offers or anything of value" that Giuliani provided to Klitschko.

Representatives of Giuliani's security company visited the State Emergency Service of Ukraine in 2017, according to the agency's website. A year later, there's a picture of Giuliani on Pruss' website in a New York conference room with an official from Kharkiv, Ukraine's second largest city. Pruss said he made it all happen.

And when Giuliani met with Ukraine's then-President Petro Poroshenko in late 2017, there’s Pruss sitting at the end of the table, in a picture first published by Poroshenko’s office.

But he said reports that he arranged for Giuliani to speak at an annual Kremlin-backed security conference in Armenia in October that also featured Russian President Vladimir Putin are inaccurate and concerns about it overblown.

Giuliani spoke at the event in 2018 but this year he pulled out at the last minute once a White House whistleblower came forward accusing Giuliani of carrying out a shadow foreign policy in Ukraine to help Trump's re-election.

Pruss said yes, he attended the conference and was planning to meet Giuliani there, but he did not arrange the appearance.

"There was nothing wrong about the Armenian conference. They do it all the time. It is about security cooperation and investments. Nothing about Russia or U.S. or Ukraine," he said in a text exchange.

In June, Pruss said he met Giuliani in a hotel lobby in Paris. Giuliani was with two Florida businessmen: Lev Parnas and Igor Fruman, two Giuliani associates who have since been charged with campaign finance violations linked to an alleged effort to inject foreign money into a U.S. election. The two have also been linked to a smear campaign against the then-U.S. ambassador, Yovanovitch.

Rudy Giuliani at a meeting with former Ukraine President Poroshenko, and Vitaly Pruss sitting at the end of the table to Giuliani's far right, on Nov. 22, 2017. Archived picture from Ukranian Presidential page

Pruss said before that meeting he had not heard of the two men. "I haven't run into them during my work at all," he said. And he said he doesn't know who was funding them: "No idea. Tell me if you find out. I'm interested to know."

But he said he is sure it wasn't Russia. "Kremlin doesn't work with people like them. It is too low for Kremlin."

Pruss said he finds the impeachment drama "disgusting," and does not believe Ukrainian President Volodymyr Zelenskiy was coerced. He said in addition to Zelenskiy's public statements that he was not pressured to investigate Hunter Biden, he has heard from those in Zelenskiy's inner circle who add to the chorus of "no pressure." But he said Trump's offer to Zelenskiy to have Attorney General William Barr help the Ukrainian government look into Hunter Biden was "beneath him."

Instead, Trump "should have had someone else do it," he said.

'The case is closed'

As the Gump of the Trump-Ukraine saga, Pruss has also crossed paths with Team Trump's main target — Hunter Biden.

Pruss' LinkedIn page has an entry from eight years ago showing a joint venture with Rosemont Realty, which was partially managed by Devon Archer, Hunter Biden's close friend. Pruss said that's when he encountered the younger Biden, but he said he did not introduce Biden to Burisma.

Unlike Giuliani, Pruss said he is reluctant to call for any investigation into Burisma, his friend Zlochevsky's natural gas company.

"They have been investigated. The case is closed. I don't know details. Important thing, they are largest independent gas company in Ukraine. Very essential for conflict with Russia. They have to be supported not attacked," he said.

As for Hunter Biden, he said there's no crime to investigate. "Whatever he did in Ukraine was highly unethical," he said, "There was no crime but very bad judgment."

Despite probing by Trump associates, there is no evidence that Hunter Biden or his father, the former vice president and current presidential candidate, acted improperly or violated any laws.

Meanwhile, in politically charged congressional hearings in Washington, Giuliani's activities in Ukraine have come under intense scrutiny, with Democrats accusing Trump's personal lawyer of pressuring Ukraine to dig up dirt on the Bidens.

But Pruss, who watched part of the hearings on television, said he doesn't have anything to do with what transpired between Trump, Giuliani and Zelenskiy.

"I'm totally irrelevant to this story."