Lev Parnas, ex-Rudy Giuliani ally, wants to testify against Trump to win leniency. Sound familiar?

A true believer who claimed he was carrying out Donald Trump’s instructions.

A loyal fixer who regularly attacked Trump’s enemies.

And a federal defendant, who, after a dramatic and public change of heart, blamed his actions on Trump.

Lev Parnas, meet Michael Cohen.

Parnas, an associate of President Donald Trump's personal lawyer Rudy Giuliani, has a lot in common with Cohen, Trump's former attorney and problem-fixer.

Both have been involved in political scandals as they faced criminal charges. Both have tried to cooperate with prosecutors in order to get leniency in their cases. And both have expressed regret for having trusted Trump.

Parnas, a Soviet-born businessman, helped Giuliani pressure Ukrainian officials to announce an investigation into the family of former Vice President Joe Biden, a potential Democratic opponent in this year's presidential race.

Now, facing federal charges that could land him in prison, Parnas has turned over documents that could prove critical in the Senate impeachment trial scheduled to begin Tuesday.

Rep. Adam Schiff, D-Calif., the lead manager for the House, said Thursday his team would consider whether to press the Senate to allow Parnas to testify.

Parnas said in recent media interviews that it's time to tell the truth about Trump's involvement in the effort to get the Ukrainian government to announce an investigation into Biden's family.

The articles of impeachment against Trump accuse him of withholding a White House visit and nearly $400 million in military funding unless Ukraine President Volodymyr Zelensky announced that investigation.

But Parnas' Road-to-Damascus moment also appears aimed at winning leniency in the criminal case that accuses him of scheming to funnel hundreds of thousands of dollars to U.S. political campaigns and candidates. Parnas has pleaded not guilty.

Parnas' defense attorney, Joseph Bondy, did not respond to messages seeking comment. However, he told The New York Times: "We very much want to be heard" in the Southern District of New York, where Parnas has been charged.

"We very much want to provide substantial assistance to the government," Bondy said.

Will prosecutors listen?

“This was clearly his audition to get on the government’s team and provide substantial assistance,” David Weinstein, a former federal prosecutor in Miami, said.

"Although the information he is providing to Congress has really nothing to do with what he is charged with, he is nevertheless making a case that his cooperation with the impeachment inquiry should be worth some consideration in his pending criminal case," Weinstein said.

Cohen turned over evidence against Trump; it didn't win him leniency

If Cohen's experience is any guide, federal prosecutors in New York won't necessarily agree to designate Parnas a cooperating witness and ask a judge for leniency.

Cohen pleaded guilty in 2018 to orchestrating payments to silence adult film star Stormy Daniels and former Playboy model Karen McDougal, both of whom claimed to have had sexual affairs with Trump. Cohen told Congress and prosecutors he did so at Trump’s direction. Trump denied their claims.

Cohen also admitted he had lied to Congress, deceived banks from which he sought loans, violated campaign finance laws and lied to the government to avoid paying taxes.

He offered to cooperate with prosecutors, and in early 2019, he turned over documents that appeared to implicate Trump in the hush money scheme. In congressional testimony, Cohen painted a damning portrait of his former boss, calling Trump a “racist,” a “con man” and a “cheat.”

But none of it convinced prosecutors to recommend a lesser punishment, in part because Cohen wouldn't reveal everything he knew.

To avoid a similar fate, Parnas would have to come clean about his role in the alleged campaign finance scheme and provide details about others who were involved. That includes the three co-defendants who joined him in entering not-guilty pleas.

New York prosecutors made those conditions clear in a December 2018 legal memo filed shortly before Cohen was sentenced to three years in prison.

"In order to successfully cooperate with this office, witnesses must undergo full debriefings that encompass their entire criminal history, as well as any and all information they possess about crimes committed by both themselves and others," they wrote.

Cohen now is battling for a reduction in his sentence. Prosecutors oppose it.

Glen Kopp, a former Manhattan federal prosecutor, noted that both Cohen and Parnas have found themselves simultaneously embroiled in criminal cases and political firestorms. Both appeared to seek "credit in the criminal context for cooperation in another context," he said.

“Just because you’re helpful in one entity doesn’t mean SDNY will consider you sufficiently cooperative from their standpoint," Kopp said. The Southern District of New York "requires complete reckoning. There can be nothing held back. For some people, they draw a line on certain things. For SDNY, that’s not acceptable.”

Parnas says Trump, Pence and Barr knew of scheme, but is he credible?

Parnas gave Congress thousands of pages of records that provided details of his and Giuliani's efforts to press Ukrainian officials for an investigation of Biden's family, as well as the secret drive to oust Marie Yovanovitch as the U.S. ambassador to Ukraine. He also asserted that Trump knew what he and Giuliani were doing.

But there are questions about Parnas' credibility and apparent gaps in the evidence he has turned over.

During an interview with MSNBC's Rachel Maddow, Parnas alleged that Trump "knew exactly what was going on" as he and Giuliani worked on the president's behalf in Ukraine. He contended that Vice President Mike Pence also knew, and he asserted that Attorney General William Barr "was basically on the team."

However, Parnas told The New York Times that he stated Trump knew about the scheme because Giuliani assured him of it.

In response, White House press secretary Stephanie Grisham said, "These allegations are being made by a man who is currently out on bail for federal crimes and is desperate to reduce his exposure to prison."

Speaking to reporters Thursday, Trump again said he doesn't know Parnas. Bondy responded by tweeting a video showing his client with his arm around the president at a Mar-a-Lago event.

Marc Short, Pence's chief of staff, said Parnas "will say anything to anybody who will listen in hopes of staying out of prison."

The Department of Justice said Parnas' statements about Barr were "100% false."

And Giuliani? “I pay no attention to him,” he said in a text message to USA TODAY on Thursday. “He’s lying.”

A formal effort to cooperate with prosecutors could also require Parnas to undergo a full debriefing on a checkered history of civil lawsuits. The cases include a New Jersey family trust's effort to recover more than $678,000 Parnas owes for a movie loan.

The movie, tentatively titled "Anatomy of an Assassin," was never produced. The Pues Family Trust has spent years pursuing Parnas for the money. It recently even tried to seize the bail money his family posted in the campaign finance scheme case.

Rudy Durand, a California-based writer and film producer, testified as a witness for the family trust. He testified "that at one time he liked and trusted Lev, but that he later found him to be a con artist," according to a 2015 federal court decision in the case.

However, Bruce Udolf, a former federal prosecutor who served as an associate independent counsel in the Clinton Whitewater investigation, said Parnas is no different than any other key witness to wrongdoing.

"There is an old saying among prosecutors: ‘Swans don’t swim in the sewers,'" Udolf said. "That applies here. Usually, these are the kind of people you need to prove your case."

This article originally appeared on USA TODAY: Lev Parnas provides evidence for impeachment, but is he credible?