The FBI has fired Peter Strzok, a top agent who had investigated the Trump campaign’s Russia ties until the discovery that he had sent politically charged text messages to a colleague.

Strzok’s attorney Aitan Goelman says in an emailed statement that on late Friday afternoon, the deputy director of the FBI ordered Strzok’s firing, even though the FBI’s disciplinary office had recommended a less severe punishment.

The government hasn’t yet commented on the specifics of Strzok’s firing. But President Trump sent triumphant tweets Monday praising the decision and asking whether the “Witch Hunt” will now “be dropped.”

Agent Peter Strzok was just fired from the FBI - finally. The list of bad players in the FBI & DOJ gets longer & longer. Based on the fact that Strzok was in charge of the Witch Hunt, will it be dropped? It is a total Hoax. No Collusion, No Obstruction - I just fight back! — Donald J. Trump (@realDonaldTrump) August 13, 2018

Just fired Agent Strzok, formerly of the FBI, was in charge of the Crooked Hillary Clinton sham investigation. It was a total fraud on the American public and should be properly redone! — Donald J. Trump (@realDonaldTrump) August 13, 2018

Behind the scenes, Strzok had played a central role in both the Hillary Clinton email investigation and the counterintelligence investigation into the Trump campaign and Russia. He also briefly served on special counsel Robert Mueller’s team last year.

For much of that time, though, Strzok was texting his co-worker and lover Lisa Page privately expressing his contempt for Trump. Once the Justice Department learned of these texts, Mueller removed Strzok from his team. Later, news of the texts broke publicly, and Trump and his allies have been furiously attacking Strzok ever since, arguing that his “bias” taints the larger Russia investigation.

An inspector general report released in June harshly criticized Strzok and expressed concern about his potential bias, but found no evidence that his political views affected his investigative decisions. However, that report focused primarily on the Clinton investigation; the IG is reviewing the Trump-Russia probe separately, and that review is not yet completed.

Strzok’s firing won’t have any direct impact on the Mueller investigation, from which he was removed about a year ago. He had already been transferred away from counterintelligence to a quiet posting in the human resources division as a punishment.

Still, Strzok is the latest addition to a now-lengthy list of top Justice Department officials who have been fired after coming under attack from the president, including FBI Director James Comey and Deputy FBI Director Andrew McCabe — which will naturally raise some questions about whether there was improper political influence in Strzok’s firing.

Who is Peter Strzok?

Strzok has served in the FBI for more than two decades, and eventually became the lead agent on the bureau’s counterespionage team. It was there that he had a major role in, first, the Hillary Clinton email investigation, and second, the counterintelligence investigation into the Trump campaign’s ties to Russia.

Strzok was a highly regarded agent with a very good reputation — but he had a secret. Through much of this time, he’d been having an affair with a co-worker: Lisa Page, who worked for then-Deputy FBI Director Andrew McCabe and was briefly assigned to Mueller’s probe too. (Both Strzok and Page are married to other people.)

On their work devices, Strzok and Page exchanged thousands of text messages in which they frequently discussed investigations they were both involved in — and shared their views on politics in general. And it turns out that neither were fans of Trump — in fact, they were appalled by him, and said so repeatedly. (You can read the publicly released texts here.)

FBI officials are of course allowed to have their own opinions about politics, though writing them out on work devices and intermingling them with discussions of the sensitive investigations involving those political figures doesn’t really look great. Yet some of Strzok’s texts arguably have more troubling implications.

In one particular late-night exchange from early August 2016, Page expresses fear that Trump will win the presidency, and Strzok answers, “No. No he won’t. We’ll stop it.” If by “we,” Strzok meant the FBI — which had opened its investigation into the Trump campaign’s Russia ties just over a week earlier — that poses the question of whether Strzok hoped to impact the election through his work. (Strzok has claimed that he merely meant the American electorate would stop Trump from winning, by voting against him.)

In any case, after Justice Department Inspector General Michael Horowitz, who was reviewing FBI leaks and the bureau’s handling of the Clinton email probe, discovered the texts last summer, Mueller was evidently sufficiently disturbed that he removed Strzok from his team immediately. (Page had already left Mueller’s team at that point.)

Do Strzok’s texts mean the FBI was biased against Trump?

Word of the Strzok-Page texts first leaked out in December 2017, and the story became a media sensation. It was seized on especially by the president and his allies, as they’ve sought to discredit the Russia investigation by alleging supposed wrongdoing by the Justice Department, the FBI, or Obama administration officials.

Why was the FBI’s sick loser, Peter Strzok, working on the totally discredited Mueller team of 13 Angry & Conflicted Democrats, when Strzok was giving Crooked Hillary a free pass yet telling his lover, lawyer Lisa Page, that “we’ll stop” Trump from becoming President? Witch Hunt! — Donald J. Trump (@realDonaldTrump) June 18, 2018

How can the Rigged Witch Hunt proceed when it was started, influenced and worked on, for an extended period of time, by former FBI Agent/Lover Peter Strzok? Read his hate filled and totally biased Emails and the answer is clear! — Donald J. Trump (@realDonaldTrump) July 11, 2018

The allegation made by Trump’s allies is that Strzok would naturally have tried to get Hillary Clinton off the hook in the email investigation, while trying to “get” Trump with the Russia probe, for political reasons.

But when it comes to Strzok’s investigative work, little evidence has emerged so far that he actually did anything improper.

Inspector General Horowitz’s exhaustive review of the Clinton email probe found that “Strzok was not the sole decisionmaker” for the key Clinton email probe decisions — he had a supervisor and others on his team all along. Additionally, Horowitz wrote, Strzok and Page sometimes “advocated for more aggressive investigative measures.”

Horowitz did conclude that he didn’t “have confidence” that one Strzok decision — to prioritize the Trump-Russia probe over reviewing new Clinton emails on Anthony Weiner’s laptop — “was free from bias.” But he also couldn’t show that there was bias there. (After all, there are legitimate arguments that pursuing active Russian interference in the final weeks of the election was the right call, and the new Clinton emails turned out to be unimportant when they were reviewed.)

The messages also demonstrate that Strzok truly was concerned about Russian interference with the election — that is, that he wasn’t just contriving a bogus investigation to hurt Trump’s prospects. “F*cking conniving cheating savages. At statecraft, athletics, you name it,” he wrote.

In the end, the full story of how exactly Strzok was fired — and whether there were improper private influences on the process — remains unclear. Still, even Strzok’s defenders should reckon with the fact he acted remarkably irresponsibly and that Mueller concluded very quickly from the texts that his removal from the probe was merited. And now, his decades in the FBI have come to an end.