Romanian hacker Guccifer’s claims that he hacked into Hillary Clinton’s private email server could bolster a potential criminal case against Clinton for mishandling classified information, according to former U.S. prosecutors.

"The question is if a guy like that can [hack into] it, who else did it?" said Joseph diGenova, former U.S. Attorney for Washington, D.C.

Matthew Whitaker, former U.S. Attorney for the Southern District of Iowa, said the hacker’s allegations would "confirm what most people have believed to be true, which was that this email server was not secured like you would expect it to be. That it was opened and had been looked at by at least people who don’t have American interests at heart."

Guccifer, whose real name is Marcel Lehel Lazar, was extradited to the United States in March. He is charged with breaching the email accounts of a number of political figures, including long-time Clinton advisor Sidney Blumenthal.

Lazar said in a Fox News interview published Wednesday that he also infiltrated Clinton’s email server in early 2013, although his claim has not been confirmed and he has not been charged with doing it.

The FBI has been investigating whether classified and national security information was mishandled over Clinton’s private server.

DiGenova said the timing and circumstances of Lazar’s sudden extradition suggests it was related to the FBI probe.

"The FBI found him, actually brought him over to the United States, actually quite early. Generally speaking they don’t bring back hackers to the United States, unless there’s been some huge financial crime," diGenova said. "I’m sure he’s there to provide some sort of context for the ongoing investigation."

Lazar, who was first charged by the United States in 2014, was in the middle of a seven-year prison sentence in Romania at the time of his March extradition.

"Bringing him back before his sentence has expired … is pretty unusual, and clearly it’s related to the Clinton server," diGenova said.

DiGenova noted that Lazar’s case is before the Eastern District Court of Virginia, "which means that the venue for all other cases related to his will be Virginia." He said the court is the most likely venue if Clinton’s email investigation leads to charges.

Whitaker said the FBI would "have a lot of interest [in talking to Lazar about Clinton’s server] based on the little bits provided to explore."

He said details about the server’s structure would be particularly valuable.

"If some of those basic facts appear to be true, I think the FBI would find him more credible and explore what else he saw," Whitaker said.

It is unclear why Lazar chose to go public with his claim now. He has previously boasted about his high-profile hacking victims in interviews and jailhouse letters but did not mention accessing Clinton’s emails.

A spokesperson for Clinton denied Lazar’s story and noted that the hacker never publicly released emails from Clinton’s server, as he has done with other political figures.

"There is absolutely no basis to believe the claims made by this criminal from his prison cell. In addition to the fact he offers no proof to support his claims, his descriptions of Secretary Clinton's server are inaccurate. It is unfathomable that he would have gained access to her emails and not leaked them the way he did to his other victims," the Clinton campaign told Fox News on Wednesday.

Lazar has pleaded not guilty to the federal hacking charges. In his interview with Fox News, he indicated that he would be open to a plea agreement and is willing to cooperate with federal authorities. He also claimed he has a hidden collection of highly-sensitive information that he has not shared with the U.S. government.

The hacker told Fox News that getting access to Clinton’s server was "easy" and he did it multiple times.

"For me, it was easy … easy for me, for everybody," Lazar told Fox News, adding that he did not find the content interesting.