One of the FBI’s top investigators tapped by special counsel Robert Muller to investigate Russian interference in the elections has left the team, according to a report.

Sources told ABC News that Peter Strzok — who had just been tapped about a month ago — is now working for the FBI’s human resources division.

It is not yet known why Strzok left the team. He had supervised the investigation into Hillary Clinton’s emails last year.

According to ABC News, Strzok has spent much of his law enforcement career working counterintelligence cases and has been “unanimously praised” by government officials who spoke with ABC News.

He was chief of the FBI’s counterespionage section last year when he oversaw the investigation into Clinton’s private server, which she had set up in her basement to circumvent normal State Department email practices. He also took part in the FBI interview of her, according to ABC.

There is no indication that the investigation is ending or of what caused Strzok’s departure. Last week, Mueller’s team executed a search warrant at President Trump’s former campaign manager’s Virginia home.

The team has faced accusations of bias, with at least a handful of its members having donated to either Clinton, Democrats, or the Democratic National Committee.