 -- Special counsel Robert Mueller has now lost a second official that he brought in from the FBI to help investigate Russia’s alleged meddling in last year’s presidential election, ABC News has learned.

The latest FBI veteran to leave, Lisa Page, was described by media accounts in June as a trial attorney with “deep experience [in] money laundering and organized crime cases.” She was part of what Wired magazine called Mueller’s “investigatory dream team.”

But weeks ago, Page left the Special Counsel’s office and returned to work in the office of the FBI’s general counsel, sources said. According to one source, Page joined Mueller’s team on a short, temporary assignment and always expected to return as soon as that assignment ended.

Page’s departure came around the same time that one of the FBI’s top investigators also left the team, as first reported by ABC News last month.

Peter Strzok had been tapped by Mueller just weeks earlier to help lead the wide-ranging probe.

It's unclear why Strzok stepped away from Mueller's team of nearly two dozen lawyers, investigators and administrative staffers. Strzok, who has spent much of his law enforcement career working counterintelligence cases and has been unanimously praised by government officials who spoke with ABC News, is now working for the FBI's human resources division.

One source told ABC News today he’s sorry Mueller’s team no longer has Strzok’s experience and insight at its disposal.

Strzok is no stranger to complex and controversial investigations.

As chief of the FBI's counterespionage section last year, he helped oversee the FBI's investigation into Hillary Clinton's use of a private email server when she was the secretary of state, and he took part in the bureau's interview of her.

Within weeks of the end of the Clinton probe, Strzok found his office facing a new challenge: Investigating Russia's alleged efforts to influence last year's presidential election, including hacking of Democratic National Committee computers.

The FBI declined to comment for this article.