Special Counsel Robert Mueller’s office is remaining tight-lipped about the circumstances surrounding the summertime firing of Mueller team member Peter Strzok.

The former counterintelligence official was exposed over the weekend for exchanging anti-Trump and pro-Hillary Clinton text messages with his mistress, an FBI lawyer who also worked on Mueller’s all-star investigative unit.

The revelation has caused shockwaves because of Strzok’s central importance to the FBI’s two highest profile investigations: the Clinton email probe and the investigation into Russian interference in the presidential campaign.

The scandal is not likely to go away soon, especially as the details of Strzok’s work on both of those FBI investigations come to light.

Strzok’s misconduct poses the first legitimate setback to Mueller’s investigation, which kicked off in May and has secured two indictments and two guilty pleas against Trump associates.

If Mueller wants to maintain the integrity of his investigation, he should answer six questions about Strzok.

Why was Strzok’s demotion kept secret for nearly four months?

Strzok’s departure from Mueller’s team was first reported on Aug. 17 by ABC News. But the explanation for the personnel change remained a mystery for months, until The New York Times and Washington Post reported about Strzok’s text messages over the weekend. Strzok is now working in the FBI’s human resources division.

Mueller’s office had refused in the interim to comment on Strzok’s departure. That didn’t change this week as the special counsel’s office has refused to provide details about Strzok.

Are Strzok’s activities an optics problem or something much worse?

Strzok is far from the only Mueller team member who appears to have overt political leanings. It has been well documented that numerous Mueller prosecutors have donated to Democratic political candidates, including Clinton and Barack Obama.

But for some reason, Strzok’s private comments are of greater concern to Mueller than some of his prosecutors’ political activity.

It could be that Strzok’s text messages are so beyond the pale that Mueller could not ignore them. It could also be that Strzok’s foundational role on the Trump-Russia unit threatens to sully the integrity of the entire investigation.

Strzok was on the ground floor of the Russia investigation when it was opened at the end of July 2016.

CNN reported that Strzok, who before his demotion was the No. 2 counterintelligence official at the bureau, signed the documents that officially opened the probe. (RELATED: Anti-Trump Text Messages Show Pattern Of Bias On Mueller’s Team)

In his top role, Strzok would have been directly involved in the shaping of the investigation. He also would likely have been one of the first FBI officials to come into contact with the infamous Steele dossier, a salacious but uncorroborated document that bears significantly on the collusion narrative.

Former British spy Christopher Steele began working on the dossier in June 2016 after being hired as a sub-contractor by the Clinton campaign and DNC. He briefed an FBI acquaintance on early July 2016. The New York Times has reported that the information made it to the Russia investigation team — led by Strzok — several weeks later.

It is also likely that Strzok was involved in applying for and obtaining a secret surveillance warrant against Carter Page, a former Trump campaign adviser who is accused in the dossier of colluding with the Kremlin.

Federal officials obtained the warrant in September 2016.

Page, who has vehemently denied the allegations in the dossier, told TheDC over the weekend that he is “curious…whether [Strzok’s] fingerprints” are on his warrant.

Did Strzok take part in the interview with dossier author Christopher Steele?

Perhaps one of the more important events in Mueller’s investigation is an interview conducted with Steele.

According to reporting from October, Mueller investigators interviewed Steele somewhere in Europe at some point in the summer.

The timing of that interview has taken on new significance amid the Strzok news. It is not known whether he took part in that interview, though there is a strong possibility that he did, given his central role in the investigation.

It is also not known when the FBI and Strzok became aware that Steele was working as a sub-contractor for the Democrats.

Why did the Strzok story leak a day after Flynn’s guilty plea?

The curious timing of the leak about Strzok is hard to ignore. The story hit a day after Flynn accepted a guilty plea for lying to the FBI earlier this year about his contacts with Russia’s ambassador, Sergey Kislyak, during the presidential transition period.

The obvious question is whether Mueller, the Justice Department, or the Justice Department’s inspector general waited until after the Flynn plea to disseminate the story about Strzok knowing that the revelations would have hurt prosecutors’ position at the negotiating table with Flynn’s lawyers.

Another question is whether Flynn and his legal team were aware of the Strzok development when they agreed to the plea deal with Mueller’s team.

Flynn’s lawyer, Robert Kelner, declined comment on Monday.

What’s up with this CNN report published just after Flynn was fired?

A CNN report published back on Feb. 16 suggests that Strzok did not believe that Flynn intentionally lied in his Jan. 24 FBI interview about his contacts with Kislyak.

CNN reported that though Flynn changed his story during the FBI interview, he would not be charged because he convincingly claimed that he had misremembered certain aspects of his conversations with Kislyak. (RELATED: Strzok Interviewed Michael Flynn)

Whether Strzok indeed did believe that Flynn was not lying is a question that Congress might want to ask.

Strzok also conducted interviews in the Clinton email probe with Clinton and several of her top aides. Two Clinton aides, Huma Abedin and Cheryl Mills, appear to have given misleading statements about what they knew about Clinton’s server. But contrary to what happened with Flynn, neither Abedin nor Mills faced legal ramifications for those statements. (RELATED: Clinton Aides Went Unpunished After Making Misleading Statements In Interview With Embattled FBI Agent)

Did Mueller ask the FBI and DOJ to prohibit Strzok from being interviewed by congressional investigators?

The FBI and DOJ have for months ignored requests from the House Intelligence Committee to interview Strzok. California Rep. Devin Nunes, the chairman of the committee, blasted the agencies over the weekend for “stonewalling” his requests to interview Strzok as well as FBI Deputy Director Andrew McCabe.

According to the Washington Examiner, Nunes and the Committee submitted five separate requests to interview Strzok. The agencies finally agreed to make Strzok available after the reports were published about his text messages.

But the stonewalling raise the question of whether Mueller asked the DOJ and FBI to keep Strzok from meeting with the committee.

Nunes has threatened to hold the agencies in contempt of Congress if they don’t soon provide access to Strzok and certain documents related to the dossier.

FBI Director Christopher Wray is likely to be pressed on many of the above questions on Thursday, when he testifies before the House Judiciary Committee.

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