In President Donald Trump’s first four months in office, he has fired the acting attorney general, asked dozens of US attorneys to resign (including firing a particularly prominent one he had asked to stay on), and dismissed the director of the FBI (who he had also asked to stay on).

Some of these moves weren’t actually all that unusual, at least in isolation. But when all of them are taken together, it raises the question of whether the president has been trying to impede investigations into himself or his associates by muscling out independent actors in the Justice Department.

In January, Trump fired acting Attorney General Sally Yates for refusing to defend his travel ban in court — a move that, while unusual, was aimed at someone who was soon to leave her post anyway, once Jeff Sessions was confirmed.

Then in March, Trump’s administration asked for resignations from 46 US attorneys held over from the Obama years. These are the top DOJ law enforcement officials in states or districts, who have a tradition of operating mostly independently. Again, however, there’s precedent for a new president to replace all his predecessor’s appointees. Yet the firing of US Attorney Preet Bharara was strange, because Trump had several months earlier asked Bharara to stay on in his post.

Finally, on Tuesday, Trump fired FBI director James Comey. This is the move with the least precedent and justification. The FBI director is a nonpartisan appointee who serves a 10-year term, recent new presidents have kept their predecessors’ FBI directors on, and Trump initially said he’d keep Comey on too. The only recent firing of an FBI director, in 1993, was due to alleged financial misdeeds.

Most concerning of all, Comey was fired despite the fact that he was overseeing a major investigation that touched on the Trump campaign and Trump associates’ ties to Russia. The administration’s own justification for Comey’s dismissal — that he was too tough on Hillary Clinton in the email case — is comically unbelievable, considering the president has long made the opposite argument. All this taken together raises some worrying questions about just how independent the Justice Department will be in this administration.

First was Sally Yates’s firing

On January 30 — the 11th day of Trump’s presidency — he fired Sally Yates, the holdover Obama Justice Department official who was serving as acting attorney general because Jeff Sessions hadn’t yet been confirmed by the Senate.

The reason for Yates’s firing was that she refused to defend Trump’s immigration and travel order aimed at people from seven predominantly Muslim countries in court, and argued that she wasn’t convinced the order was “lawful.”

Not only did Trump fire Yates, but the White House statement announcing her firing attacked her personally, calling her “an Obama Administration appointee who is weak on borders and very weak on illegal immigration” who “betrayed the Department of Justice.”

But it later emerged that there had been even more drama going on behind the scenes, on another topic entirely. The Washington Post reported that just four days before Yates’s firing, she had given Trump’s White House counsel, Don McGahn, a disturbing briefing — warning that then-National Security Adviser Michael Flynn was “potentially vulnerable to Russian blackmail.” Yates confirmed this account in public testimony earlier this week.

In some ways, Yates’s firing is the least unusual. She was headed for the exits as soon as Sessions was confirmed anyway. And her refusal to defend the executive order in court was indeed highly controversial and arguably insubordinate. Still, this served as an early sign that the president was not inclined to let the Department of Justice operate independently.

Preet Bharara (and the other US attorneys)

The second DOJ firing controversy of Trump’s administration erupted on March 10, 2017, when Trump’s Justice Department immediately asked for the resignations of 46 US attorneys held over from the Obama administration.

As I wrote at the time, it is perfectly normal for a new president to want to replace his predecessor’s US attorney appointees with his own, and even to ask most or all of them to resign. But the timing was remarkably abrupt — all but a few of these attorneys were dismissed immediately, even though Trump hadn’t nominated anyone to replace them (and in fact still hasn’t nominated even a single person for a US attorney post two months later).

Furthermore, one firing in particular — that of Preet Bharara, US attorney for the Southern District of New York — stood out, because Trump had told Bharara that he would keep him on during the transition. In fact, Bharara refused to step down when Sessions asked him too, and forced Trump to fire him.

Speculation soon arose that the whole batch of US attorney dismissals was done as cover to get rid of Bharara, particularly when ProPublica’s Robert Faturechi reported that Bharara had been investigating stock trades by HHS Secretary Tom Price.

The plot thickened even more when the New York Times reported that, the day before the US attorneys were asked to resign, President Trump’s office placed an unusual call to Bharara’s office (through Trump’s assistant), and asked for a call back. According to the report, Bharara reviewed Justice Department protocol and decided it would be inappropriate to return the call. The next day, he was asked to resign along with the other US attorneys.

Bharara himself suggested that something untoward was going on, sending some cryptic-sounding tweets, one of which referred to the “Moreland Commission,” which New York Gov. Andrew Cuomo created to investigate corruption in state politics and then hastily shut down as part of a political deal.

Currently, Bharara’s post is occupied on an acting basis by his deputy, Joon Kim. All but a handful of the 93 US attorneys also currently hold their jobs on an acting basis.

And now Comey

Finally, on Tuesday, Trump fired FBI Director James Comey. I explain the details and context of the firing at more length here, but suffice to say, this is the most unusual and concerning move of the three.

Though Comey had faced intense criticism over his handling of the Hillary Clinton email investigation from both Democrats and Republicans (for different reasons), it seemed he had weathered the storm. Trump reportedly told him in January that he would keep him in his post. In early March, Comey said he planned to serve out the full remainder of his 10-year term. “You’re stuck with me for another 6-and-a-half years,” he said.

Yet in March, Comey publicly dropped the bombshell that the FBI was investigating “the nature of any links between individuals associated with the Trump campaign and the Russian government and whether there was any coordination between the campaign and Russia’s efforts.”

The president has been open about his deep unhappiness with the Russia investigation in tweets and public statements. Just this week he tweeted, “The Russia-Trump collusion story is a total hoax, when will this taxpayer funded charade end?” Privately, he was even angrier, according to reporting by Politico’s Josh Dawsey, and he responded by asking the Justice Department to try to push Comey out.

Comey’s ouster calls the independence of the US’s top law enforcement institutions into serious question. And with all the firings, President Trump has sent the unmistakable message to Justice Department and other law enforcement officials that if they refuse to toe the White House line — or if they poke their nose in places the White House doesn’t want them too — they may not keep their jobs for long.