A federal prosecutor who recently worked for Preet Bharara – the former U.S. attorney who has emerged as a prominent Trump critic ever since his firing – is joining special counsel Robert Mueller’s investigation of Russian meddling in the 2016 campaign.

The special counsel’s office confirmed that Andrew Goldstein will be on detail from the Southern District of New York to work on the case. As the top public corruption attorney in the Manhattan office, Goldstein becomes the latest high-profile prosecutor to join the probe.

His old boss Bharara praised him on Twitter as a sterling choice.

“Andrew Goldstein, my corruption chief, joins Special Counsel Mueller. Best of best in every way. Fair, tough, smart,” Bharara wrote. The hire was first reported by The New York Times.

The Mueller investigative build-up, however, has raised concerns in recent weeks among Trump allies.

Former House Speaker Newt Gingrich has decried the probe as a “witch hunt,” while Trump last month complained that several investigators on Mueller’s team were donors to his 2016 rival Hillary Clinton.

MUELLER LAWYER BUILD-UP RAISES RED FLAGS

The Bharara connection could feed concerns among Trump allies.

Bharara has been critical of the president ever since he was let go in March along with dozens of other U.S. attorneys held over from the last administration. Last Thursday, he joined the bipartisan criticism of Trump’s attacks on the media, tweeting:

“Much of the issue with Trump is not about party, policy or ideology, but lack of decency, honesty, character, temperament, adulthood, shame.”

Bharara also proved prescient in an interview last month about the direction of the Mueller investigation.

Speaking on ABC News, Bharara said there’s “absolutely evidence” to launch an obstruction of justice case against Trump’s team with regard to the Russia probe.

“No one knows right now whether there is a provable case of obstruction,” he said, adding: “There’s no basis to say there’s no obstruction.”

Days later, it was reported that Mueller’s investigation was looking at the obstruction angle.

Fox News’ Catherine Herridge contributed to this report.