Ukraine’s top prosecutor said Friday that his office is "conducting an audit" of cases that have been previously investigated and closed, including the probe involving the energy giant Burisma, where Hunter Biden had served on the board.

Ruslan Ryaboshapka, the country's prosecutor general, said at a news conference that his office was instructed to review cases that have been closed, fragmented or investigated to make sure they were fairly and thoroughly handled. He said no one attempted to influence him to make the call.

DOCUMENTS HEIGHTEN SCRUTINY ON BIDEN-UKRAINE DEALINGS, INDICATE HUNTER MAY HAVE MADE 'MILLIONS'

“We are now reviewing all the cases which were closed, fragmented or investigated earlier in order to make a decision on cases where illegal procedural decisions were taken,” he said.

The office plans to review 15 cases that previously were closed, including the Burisma case. This does not yet mean Ukraine is opening a new investigation involving Burisma or the Bidens.

His comment came as the Trump White House fights an impeachment inquiry that involves allegations that President Trump used military funding as part of a "quid pro quo" with Kiev to investigate Biden and his father, former Vice President Joe Biden.

Trump has denied wrongdoing. Ukraine’s President Volodymyr Zelensky, who participated in a scrutinized phone call with Trump in July, said he never felt pressure from Trump.

Trump's key focus has been how Hunter Biden, who reportedly knew little about the energy business and the country, ended up on Burisma’s board while his father was vice president under Barack Obama. The elder Biden later pressured Ukraine to oust a prosecutor who had been looking into the company's founder, though Biden allies say this intervention was driven by corruption concerns.

CLICK HERE FOR THE ALL-NEW FOXBUSINESS.COM

It is unclear how much money Hunter Biden made while serving on the board of the firm, but reports have estimated he made up to $50,000 per month — which would be up to $600,000 a year.

Fox News has also obtained notes from an interview Trump lawyer Rudy Giuliani conducted—with Yuriy Lutsenko, the former Ukrainian prosecutor who replaced Shokin and eventually closed the Burisma probe. He said he “believes Hunter Biden receives millions of dollars in compensation from Burisma,” according to the notes.

Fox News reported Wednesday on notes from another interview Giuliani conducted with Viktor Shokin, the prosecutor Biden helped oust, in which he claimed he was told by former U.S. Ambassador to Ukraine Geoffrey R. Pyatt to back off the Burisma probe. According to interview notes, Shokin claimed Pyatt – currently the ambassador to Greece – told him to handle that investigation “with white gloves.”

Biden has acknowledged on camera that when he was vice president he successfully pressured Ukraine to fire Shokin.

The vice president threatened to withhold $1 billion in critical U.S. aid if Shokin was not fired.

"Well, son of a b---h, he got fired," Biden joked at a panel two years after leaving office.

But Biden's campaign and congressional Democrats reject Giuliani's allegations and suggestions that his intervention was tied to his son's work, maintaining that Biden was only involved due to corruption concerns surrounding Shokin and casting Giuliani's claims as "debunked conspiracy theories."

Ryaboshapka is considered a reformer and “the father of the anti-corruption strategy in Ukraine,” a former associate told the Washington Post. Another peer called him an “honest person” but expressed doubts that he has the ability to weed out corruption in the country.

"Being a good guy is not always enough," the source said.

Fox News' NaNa Sajaia, Griff Jenkins, Brooke Singman and Gregg Re contributed to this report.