Robert Mueller's Russia investigation team loses 2nd FBI veteran

Second FBI official left Special counsel Robert Mueller's team weeks ago.

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.

The FBI declined to comment for this article.