KIEV, Ukraine — Ukraine’s new chief prosecutor, who has promised to root out corruption and political favoritism in his office, said Friday that his staff will review all previous cases concerning a gas company at the heart of the impeachment inquiry into President Trump’s dealings with Ukraine.

The decision by prosecutor Ruslan Ryaboshapka does not open the criminal investigation Trump wants against Joe Biden and his son Hunter, who was a board member of the gas company, Burisma.

Instead, the “audit” of past cases involving Burisma seems more designed to show that Ryaboshapka is following up on the clean-government pledges he and President Volodymyr Zelensky made upon taking office, analysts said.

It also may buy some time for Ukrainian authorities at a sticky moment — as they deal with the aftermath of Trump’s alleged favor-trading demand for a Biden probe, while trying to keep Ukraine’s image from being too tarnished by the House impeachment inquiry.

According to text messages released on Oct. 3, former special envoy to Ukraine Kurt Volker helped set up President Trump's phone call with Ukraine. (Reuters)

But the prosecutor’s intended audience is not the White House or Capitol Hill, said Oleksiy Baganetz, a former deputy prosecutor general in Ukraine. He is striving to keep public opinion in Ukraine behind him.

“This is a political issue more than a criminal one,” Baganetz said.

Ryaboshapka reiterated Friday that he has seen no evidence of criminal wrongdoing by Hunter Biden. He added that no foreign or Ukrainian official had asked him to pursue the audit of the cases.

“We are now reviewing all proceedings that were closed, fragmented or investigated earlier, in order to make a decision in cases where illegal procedural decisions were made and to review them,” said Ryaboshapka.

Ryaboshapka, appointed by Zelensky, has a reputation as a legal reformer, and he vowed to clean up the deeply compromised system of prosecution in Ukraine.

He’s one month into the job, and his supporters want results, Baganetz said.

The reviews, however, may take time and could move far more slowly than the fast-developing political events in Washington.

Oleksandr Lemenov, an anti-corruption activist, said any attempt by outside politicians, Ukrainian or otherwise, to interfere in the business of the prosecutor’s office could prompt widespread resignations among the new, idealistic staff.

Ryaboshapka would have no desire to get caught up in American politics, said Lemenov. “Every smart top public official should understand that the story about Trump-&-Biden (read Republicans-&-Democrats) is not so fun for us,” he wrote in a text message.

Hunter Biden was invited to join Burisma’s board in 2014. The company’s principal owner, Mykola Zlo­chevsky, had served as minister of ecology and natural resources in the brazenly graft-ridden administration of President Viktor Yanukovych, who fled to Russia after being ousted.

Ryaboshapka said Friday that he was aware of at least 15 cases that were launched against Zlo­chevsky after Yanukovych’s downfall in 2014, all of which focused on the period before Biden joined the board and none of which came to anything. Zlochevsky was accused of illegally awarding licenses to his own companies.

But the chief prosecutor from 2015 to 2016, Viktor Shokin, did little to move those or other corruption cases along. Eventually, Western officials, including then-Vice President Joe Biden, sought his ouster. Shortly after Shokin was fired, the case against Burisma was closed.

That fueled Trump’s insistence that the senior Biden brought pressure on Kiev to protect his son and that a new criminal probe should be undertaken.

But a former deputy to Shokin, David Sakvarelidze, told The Washington Post that the Burisma case was shut down by Shokin’s successor, Yuri Lutsenko, after a deal was reached in which the company agreed to sell natural gas at a favorable price to companies controlled by then-President Petro Poroshenko.

That version is supported by clandestine recordings made by a businessman now in exile, Oleksandr Onyshchenko.

This is the sort of allegation that Ryaboshapka now wants to revisit.

Sakvarelidze said the furor over Trump’s demand and the attention now being paid to Burisma required some response from Ukraine. Ryaboshapka was in a position to give the least politically difficult one.

“He cannot ignore this issue,” Sakvarelidze said. “But the other question is, where will this investigation lead?”

The audit does not mark a reopening of the criminal probe. But, in theory, the prosecutor’s office could find enough evidence to bring charges against those who formerly ran it, especially if the allegation of a corrupt deal with Poroshenko is borne out.

And if a criminal case eventually emerges from this, said a former associate, Ruslan Radetzky, “It will be a Ukrainian matter, and no one else’s.”

At the news conference, Ryaboshapka was asked about correspondence that was turned over to the House on Thursday by Kurt Volker, the former special U.S. envoy for Ukraine. The text messages show that Volker helped arrange a meeting between Rudolph W. Giuliani, Trump’s attorney, and Andrey Yermak, foreign affairs adviser to Ukraine’s president, Zelensky.

“These questions,” Ryaboshapka said, “should be addressed to the authors of this correspondence.”

He said that his office “is independent of the office of the president and of political influence by that office.”

He also said he was not bothered by Zelensky calling him “100 percent my person” in the July 25 phone call with Trump.

Natalie Gryvnyak contributed to this report.