This summer, ex-FBI agent Peter Strzok filed a lawsuit suggesting his firing was political retribution for having run the bureau’s counterintelligence investigation into the now debunked allegations that Donald Trump and Russia colluded to hijack the 2016 election.

The Justice Department has responded to the lawsuit in a big way, releasing to the court presiding over the civil case Strzok’s official misconduct file that concluded the former FBI supervisor exhibited “a gross lack of professionalism and exceptionally poor judgment.”

It shows the FBI substantiated that Strzok had engaged in dereliction of duty, had committed misconduct through the expression of anti-Trump bias on his official FBI phone and committed security violations by performing official government work on personal email.

The records show one official recommended termination, and another recommended suspension for 60 days without pay. The bureau leadership chose the more severe of the two penalties, terminating Strzok last year.

The dereliction of duty citation involved Strzok’s failure, according to the FBI, to quickly follow up in fall 2016 after the belated discovery of a trove of Hillary Clinton emails on a laptop belonging to former Congressman Anthony Weiner and his wife, Clinton aide Huma Abedin.

Strzok was supervising the investigation of whether Clinton’s use of personal email for classified State Department matters created a security risk, and his failure caused an unnecessary delay to evaluate the new evidence just weeks before Election Day, the FBI concluded.

The disciplinary file included testimony from one of Strzok’s colleagues, a fellow agent, about the failure to respond to the discovery of emails. “The crickets I was hearing was making me uncomfortable because something was going to come crashing down,” the agent testified. “….I still to this day don’t understand what the hell went wrong.”

The agent testified he feared “somebody was not acting appropriately, somebody was trying to bury this” discovery of new Clinton email evidence, the files show.

Strzok offered a bevy of excuses for his inaction, including he was busy working the Trump-Russia case at the time. All were rejected. “The investigation reveals that there is no reasonable excuse for the FBI’s delay in following up on this matter,” the disciplinary file concluded.

The FBI also cited Strzok for a violation of security protocols for conducting bureau business on personal email and personal devices, putting his sensitive counterintelligence work at risk of compromise.

“The investigation uncovered numerous occasions in which you used your personal email account,” the final findings concluded.

But the disciplinary letter to Strzok that preceded his firing saved its harshest words for his expression of anti-Trump bias in official government text messages with FBI lawyer Lisa Page while they were having an affair.

The disciplinary file shows the FBI believed Strzok’s political statements on his official government phone while overseeing the Russia collusion and Clinton email probe may have caused the bureau its most lasting damage.

The letter cited pages of the most egregious texts where Strzok and Page railed against Trump and even suggested they would use their powers to have “an insurance policy” or to “stop him” from becoming president.

“Your excessive, repeated and politically charged text messages, while you were assigned as the lead case agent on the FBI’s two biggest and most politically sensitive investigations in decades, demonstrated a gross lack of professionalism and exceptionally poor judgment,” the FBI wrote Strzok.

“Your misconduct cast a pall over the FBI’s Clinton email and Russia investigations and the work of the Special Counsel. The immeasurable harm done to the reputation of the FBI will not be easily overcome,” the letter added.