When the issue arose, Strzok was taken off the Mueller team in August and he was given a job in the human resources division of the Federal Bureau of Investigation - widely viewed as a demotion internally, according to people familiar with the matter.
Some of the lawyers working for Mueller had donated to Hillary Clinton, and one had even done work for the Clinton Foundation, which was a target of the Trump campaign during the election (and may have been under investigation by the FBI as well).
ABC News reported back in August that Strzok had left the investigation, but said at the time "it's unclear why Strzok stepped away from Mueller's team of almost two dozen lawyers, investigators and administrative staffers".
The people who were briefed on the reassignment said it was due to the "discovery of text messages in which Strzok and a colleague reacted to news events, like presidential debates, in ways that could appear critical of Trump".
The texts came up during an investigation into how the FBI handled (or mishandled) the Clinton's email inquiry, which is being led by the Justice Department's inspector general, Michael Horowitz. In a busy morning of notes to his 44 million followers, Trump earlier said that "I never asked" former FBI Director James Comey "to stop investigating Flynn". Law enforcement officials who have worked with Strzok told the New York Times they've seen no evidence to suggest he let his political views influence the investigation.
The Justice Department 's Office of the Inspector General said in a statement Saturday that it has been "reviewing allegations involving communications between certain individuals, and will report its findings regarding those allegations promptly upon completion of the review of them". Mueller has been looking into Russian interference in the 2016 US presidential election since May.
During the Clinton email investigation, Page was a regular participant when Comey would hold "skinny group" meetings on the case - a small collection of advisers that gathered to address sensitive cases, according to people familiar with the case. Page reportedly left Mueller's team in July and no longer works with McCabe, while Strzok was removed from Mueller's team in August and subsequently reassigned to the FBI's HR department in an apparent demotion.