Has he delivered the most devastating blow yet to Donald Trump’s defence? Or is he merely a desperate man trying to save his skin?

Lev Parnas is the latest obscure figure to find himself thrust centre stage by the impeachment of the US president.

A close associate of Trump’s personal lawyer, Rudy Giuliani, Parnas on Wednesday added to evidence that Trump personally directed an effort to pressure Ukraine to investigate one of his political rivals.

“President Trump knew exactly what was going on,” he said in a televised interview with MSNBC’s Rachel Maddow on Wednesday. “He was aware of all my movements … I wouldn’t do anything without the consent of Rudy Giuliani or the president.”

The interview took place even as the House of Representatives transferred articles of impeachment to the Senate ahead of Trump’s trial. But who is he – and can he be trusted?

Lev – the name means “lion” in Russian – Parnas was born in February 1972 in Odessa, Ukraine, then part of the Soviet Union. His family moved to America when he was three, first to Detroit, then to New York.

When Parnas was 23, he settled in Florida. He co-founded a company called Global Energy Producers and, in 2013, another named Fraud Guarantee – reportedly so he could bury Google search results about a history of debts and court judgments against him.

Parnas had little interest in politics until Trump ran for president. Parnas attended his campaign rallies and became a donor.

“Parnas told me that he ‘bumped into’ Trump ‘plenty of times’ at events in New York over the years, but that they didn’t get to know each other until the 2016 campaign,” Adam Entous of the New Yorker reported.

After Trump’s shock win, Parnas became closer to Giuliani and worked on his behalf to collect dirt on Joe Biden and his son, Hunter, in Ukraine – which became the core of the impeachment inquiry that could lead to Trump’s removal from office.

Parnas told the New Yorker: “Because of my Ukrainian background and my contacts there, I became like Rudy’s assistant, his investigator. I don’t do anything on my own. I don’t lobby people. I go get information. I set up a meeting. I make sure that the call went right. I make sure the translation is done right.”

Documents released this week suggest that Parnas was also involved in monitoring the movements of Marie Yovanovitch, who was ambassador to Ukraine until Trump abruptly recalled her last May. Ukraine said on Thursday it has launched an investigation into alleged illegal surveillance of Yovanovitch.

Yuri Lutsenko, the former Ukrainian prosecutor general, said in an October interview that he and Parnas met for the first time with Giuliani in New York, and then later in Warsaw. Parnas became his main contact for the group, and they regularly exchanged SMS messages with articles from Ukrainian and US media.

“It seemed to me that they were close to Giuliani and they really tried to help him with finding information about issues Mr Giuliani is interested in,” Lutsenko said of Parnas and his business partner Igor Fruman.

Lutsenko claimed he was not the one who set Parnas and Fruman and Giuliani against Yovanovitch. “Giuliani and especially these two guys [Parnas and Fruman] told me they are against [Yovanovitch] as an ambassador long before our meeting,” he said. “I never asked for any activity against her … I never asked for any deal on this point.”

“I find this story very funny. How could two American businessmen dismiss the ambassador?” he said in the October interview. “How could Mr Giuliani dismiss an ambassador?”

After their meeting, he said, Parnas began asking for help organising other top-level meetings in Ukraine.

“He asked me after our presidential elections to help with meeting the newly elected president [Zelenskiy], but I told him that it’s impossible for me to help,” said Lutsenko. “We exchanged some newspaper and mass media articles, but nothing else. I never shared legal materials with them. We never spoke about their business, I don’t even know what business they’re in.”

Last October Parnas and Fruman were arrested as they tried to flee the US. They were indicted on charges of conspiracy, making false statements and falsification of records and ordered to turn over key documents to congressional investigators.

Prosecutors allege they made outsize campaign donations to Republican causes after receiving millions of dollars originating from Russia. Parnas and Fruman have pleaded not guilty.

Trump said last year: “I don’t know those gentlemen. I don’t know what they do. Maybe you will have to ask Rudy.”

But numerous photos show Trump and Parnas together. Photos released from Parnas’s phone this week show him not only with Trump but his son Donald Jr, daughter Ivanka and her husband Jared Kushner.

Parnas told Maddow on Wednesday: “I mean, we’re not friends. Me and him didn’t watch football games together. We didn’t eat hot dogs. But he knew exactly who we were. He knew exactly who I was, especially because I interacted with him at a lot of events.”