President Donald Trump’s unprecedented attacks on federal law enforcement turned even more vindictive over a series of jarring events last weekend.

The drama began with the late Friday night firing of FBI Deputy Director Andrew McCabe just 26 hours before he would have qualified for a full federal pension. It ended Sunday with a string of presidential tweets attacking McCabe, former FBI Director James Comey, and special counsel Robert Mueller. Trump had never before attacked Mueller by name in a tweet.

Taken together, the weekend’s developments show that Trump’s war with US law enforcement has entered a new phase and that the president and his loyalists feel more emboldened to attack Mueller and others working on the Trump-Russia probe directly. It also raised new fears that Trump would take the extreme step of actually firing Mueller himself — a move that both Democrats and Republicans say would spark a constitutional crisis.

“This is an escalation because it’s open warfare against the special counsel by name, and it’s capping off a 10-month effort to thwart the FBI and Mueller,” Andy Wright, a professor at Savannah Law School, told Vox. “I don’t know what happens next because we’re in uncharted territory.”

McCabe’s ouster raised eyebrows throughout Washington because of its seeming spitefulness — the move could cost him his benefits — and because it came after Trump spent months publicly calling for his head.

McCabe, according to someone close to him, never spoke with Attorney General Jeff Sessions, FBI Director Christopher Wray, or Trump about his termination. Instead, he found out after someone close to him read Sessions’s firing statement to him over the phone. The statement had already appeared on TV by that point; McCabe received an email about his ouster mere minutes before Sessions made the announcement but didn’t see it in time.

McCabe’s firing also set the stage for a dramatic escalation of Trump’s standoff with Mueller. Early Saturday morning, Trump’s lead personal lawyer John Dowd told reporters that Mueller’s probe should end, pointing to McCabe’s firing as a sign the whole investigation is tainted.

Hours later on Saturday, reports surfaced that McCabe took notes of his interactions with Trump and gave them to Mueller. McCabe’s onetime boss Comey also kept notes about his interactions with the president because he worried Trump would lie about them.

It’s not clear if McCabe had similar concerns, but he might be able to corroborate Comey’s claim that Trump pressured him to end the FBI’s probe into former National Security Adviser Michael Flynn. If he does that, it makes Mueller’s obstruction of justice case much stronger.

And last but certainly not least, Trump spent his Sunday morning firing off tweets directed at McCabe, Comey, and Mueller. Trump accused Comey of lying under oath, questioned the existence and validity of McCabe’s memos, and criticized Mueller by name for allegedly filling the ranks of his team of prosecutors and investigators with Democrats.

Mueller and Comey didn’t comment, but McCabe issued a fiery statement on Friday arguing that he’d been purposely and cruelly “singled out” by the president.

If you missed any of last weekend’s events, don’t worry. Here’s a guide to one of the most dramatic — and potentially most legally and politically significant — weekends in months.

Sessions fired McCabe — and McCabe fired back at Trump

The Trump administration argues that there were legitimate grounds for firing McCabe right before he’d be eligible for his full pension.

Here’s why: Justice Department Inspector General Michael Horowitz found that McCabe inappropriately allowed two top officials to speak to reporters in 2016 about his decision to open a case into the Clinton Foundation. This incident was under investigation as part of a broader look into how the FBI and Justice Department handled themselves during the most recent presidential election.

According to reports about the watchdog’s conclusion, which is still under wraps, McCabe apparently misled investigators during an interview with the inspector general, a charge McCabe denies. Still, that led to a recommendation that Sessions should fire McCabe — a recommendation Sessions acted on Friday night.

“The FBI expects every employee to adhere to the highest standards of honesty, integrity, and accountability. As the OPR proposal stated, ‘all FBI employees know that lacking candor under oath results in dismissal and that our integrity is our brand,’” Sessions said in a statement provided by the Justice Department.

It’s worth noting that Sessions had to recuse himself from the Mueller probe due to his interactions with Russians as a member of the Trump campaign, which calls into question his involvement in McCabe’s ouster.

Leading Democrats and Republicans criticized the timing of McCabe’s firing, which seemed vindictive given how many of the benefits he earned over the course of a two-decade career are now at risk.

Beyond the timing, though, many Democrats also warned that the move looked like political payback by a White House that has been attacking McCabe by name for months.

Trump’s anger toward McCabe goes back to a long-running controversy over his wife’s alleged political ties to Hillary Clinton. In 2015, McCabe’s wife ran for a state Senate seat in Virginia, backed in part with money provided by the state Democratic Party and Gov. Terry McAuliffe, a prominent Clinton ally.

Trump and other Republicans have argued that those financial donations meant that McCabe was a partisan secretly harboring an anti-Trump agenda. Trump also made it personal: He once asked McCabe what it was like to have a “loser” wife.

Trump, who has tweeted about his anger over the McCabes for months, made reference to his longstanding ire again on Saturday.

The Fake News is beside themselves that McCabe was caught, called out and fired. How many hundreds of thousands of dollars was given to wife’s campaign by Crooked H friend, Terry M, who was also under investigation? How many lies? How many leaks? Comey knew it all, and much more! — Donald J. Trump (@realDonaldTrump) March 17, 2018

Beyond that, McCabe was ensnared in controversy over text messages that Peter Strzok, an FBI agent, sent to federal attorney Lisa Page. Strzok had mentioned someone named “Andy” in a text message to Page, suggesting there was a discussion about Trump — and not a positive one — in McCabe’s office. Conservative media harped on this text, implying that McCabe was part of a grand anti-Trump conspiracy.

Others in the GOP came to McCabe’s defense after the firing. “He should have been allowed to finish through the weekend,” Republican Sen. Marco Rubio told Meet the Press on Sunday. “If that report would’ve indicated wrongdoing or something that was actionable, there are things that could’ve been done after the fact. But, you know, 48 hours to go before retirement, I would’ve certainly done it differently given the fact there’s still this report out there that hasn’t come in.”

The most impassioned defense came from McCabe himself. In a defiant statement about Sessions’s decision, McCabe said he had been targeted by the president for political, and possibly illegal, reasons:

Here is the reality: I am being singled out and treated this way because of the role I played, the actions I took, and the events I witnessed in the aftermath of the firing of James Comey. The release of this report was accelerated only after my testimony to the House Intelligence Committee revealed that I would corroborate former Director Comey’s accounts of his discussions with the President. The OIG’s focus on me and this report became a part of an unprecedented effort by the Administration, driven by the President himself, to remove me from my position, destroy my reputation, and possibly strip me of a pension that I worked 21 years to earn. The accelerated release of the report, and the punitive actions taken in response, make sense only when viewed through this lens.

McCabe might ultimately have the last word about his involvement in the Trump-Russia probe (more on that below). In the meantime, Trump’s legal team is already trying to use his firing to disrupt — and possibly terminate — the special counsel’s work.

Trump’s lawyer is pushing to end Mueller’s investigation

Within hours of McCabe’s firing, Dowd, Trump’s personal lawyer, asked Deputy Attorney General Rod Rosenstein to kill the Justice Department’s Russia probe. (Rosenstein has direct authority over the Mueller probe.)

Dowd, in an email to reporters, linked McCabe to the Russia investigation and blamed Comey for making up a case:

I pray that Acting Attorney General Rosenstein will follow the brilliant and courageous example of the FBI Office of Professional Responsibility and Attorney General Jeff Sessions and bring an end to alleged Russia collusion investigation manufactured by McCabe’s boss James Comey based upon a fraudulent and corrupt dossier.

Dowd had initially told the Daily Beast that he was speaking on behalf of Trump as his “counsel,” only to backtrack after his statement was published and say he was actually speaking for himself. That matters because Trump has repeatedly denied that he’s trying to get rid of Mueller, largely relying on Republican allies to make the case for him.

Dowd is a longtime Washington lawyer, having helped Sen. John McCain confront the Keating Five banking scandal as far back as 1990. He joined Trump’s team to combat the Mueller probe in June, taking the lead as Trump’s chief outside lawyer (Trump is also represented by White House counsel Don McGahn and Ty Cobb, who handles the White House’s response to Mueller’s investigation).

It’s not the first time Dowd’s comments about Mueller have sparked a political controversy. In December, Trump tweeted that he “had to fire” Flynn, the former national security adviser, because Flynn had lied to the FBI.

I had to fire General Flynn because he lied to the Vice President and the FBI. He has pled guilty to those lies. It is a shame because his actions during the transition were lawful. There was nothing to hide! — Donald J. Trump (@realDonaldTrump) December 2, 2017

The tweet created a headache for the White House because of the implied timing. Flynn left the White House on February 13, 2017. Trump met with Comey the next day, and according to notes Comey took after the meeting, he asked Comey to “let Flynn go.”

That would mean that Trump knew Flynn had committed a felony — lying to the FBI — when he asked Comey to drop the case, suggesting that the president tried to knowingly obstruct justice.

Dowd later told NBC News that he had dictated the tweet to Trump’s social media director, Dan Scavino, and that Trump didn’t know that Flynn had lied to federal agents.

Dowd also told Axios in December that Trump “cannot obstruct justice because he is the chief law enforcement officer” of the US, a claim that was heavily disputed by legal experts who spoke to Vox. Former FBI agent Asha Rangappa said the president’s position of power does not mean he can do anything he wants.

“The president is not above the law and can indeed be guilty of obstructing justice,” Rangappa said.

McCabe recorded his interactions with Trump

Lordy, it looks like McCabe has memos.

On Saturday afternoon, multiple news outlets reported that McCabe took notes about his interactions with Trump. We don’t know what they contain. But there’s at least one person who does: Mueller, because McCabe reportedly handed over his notes to the special counsel’s team. Mueller’s team has also reportedly interviewed McCabe and asked him questions about how Trump fired Comey.

That’s potentially important because the memos can give Muller even more insight into how Trump dealt with FBI leadership and if at any point he attempted to end the probe. Recall that one of Comey’s memos, which was initially reported by the New York Times in May 2017, said the president had encouraged Comey to drop the investigation into ousted Flynn. Comey also revealed that Trump requested a pledge of loyalty from Comey, which Comey refused to offer.

McCabe could corroborate Comey’s claim that Trump tried to obstruct justice by verifying the contents of Comey’s memo and recalling what Trump said to Comey. Apparently, McCabe’s memos also contain information about his conversations with Comey. If McCabe tells Mueller all of this, the special counsel might have an even stronger case if he decides to take the historic step of trying to indict a sitting president.

Trump, for his part, doesn’t believe there are memos at all. He mentioned as much during a furious tweetstorm on Sunday, which brings us to...

Trump tweets his rage

On Sunday, Washington woke to a Trump tweetstorm in which the president reiterated his claim that the Mueller investigation was a “WITCH HUNT” and defended the McCabe firing.

The Mueller probe should never have been started in that there was no collusion and there was no crime. It was based on fraudulent activities and a Fake Dossier paid for by Crooked Hillary and the DNC, and improperly used in FISA COURT for surveillance of my campaign. WITCH HUNT! — Donald J. Trump (@realDonaldTrump) March 18, 2018

Trump’s tweets included a slew of previously debunked allegations and misleading claims.

Trump’s tweet referenced the Foreign Intelligence Surveillance Act (FISA) court — which reviews requests from the FBI to spy on Americans when there’s evidence that they might be working with a foreign government — that approved surveilling former Trump campaign aide Carter Page in October 2016.

The FBI used information from a highly controversial dossier, written by former British intelligence agent Christopher Steele, alleging Page met with Russian officials and that the Kremlin has compromising information on the president.

Republicans claim that the FBI didn’t tell the FISA judge enough about the information and that it was the main reason they got the warrant, while Democrats say the FBI acted properly. They pointed to a series of meetings between Page and a Russian intelligence operative in 2013 as one of many reasons beyond the Steele dossier that Page was of interest to investigators.

The warrant request itself is classified and hasn’t been made public.

Trump also continued to insist that there was “no collusion and there was no crime” associated with his campaign.

When House Republicans closed their Russia probe on Monday, they said they had found no proof of collusion, although the Senate and Mueller team are still investigating.

There have been crimes, though.

Four people tied to the Trump campaign have pleaded guilty to crimes as part of the Mueller probe, while Trump’s former campaign chair Paul Manafort has been indicted.

Three of the four have admitted to lying to investigators. The fourth, Manafort’s former right-hand man Rick Gates, also pleaded guilty to “conspiracy against the United States.”

New York Times reporter Maggie Haberman wrote that Trump’s team had recently received questions from Mueller for a potential interview with Trump, which may have set off the president.

Trump also used Twitter to push a running argument among conservatives that Mueller’s probe is biased because some of the lawyers on his team are supposedly Democrats.

Why does the Mueller team have 13 hardened Democrats, some big Crooked Hillary supporters, and Zero Republicans? Another Dem recently added...does anyone think this is fair? And yet, there is NO COLLUSION! — Donald J. Trump (@realDonaldTrump) March 18, 2018

The emphasis on the political leanings of the investigators is not new. As Vox reported in December:

The attacks began over the summer when reports showed that some of Mueller’s top prosecutors previously donated to Democrats. For example: James Quarles, a top lawyer on Mueller’s team with experience in the Watergate case, donated thousands of dollars to the Michael Dukakis, Al Gore, John Kerry, Barack Obama, and Hillary Clinton campaigns. Critics said such donations meant that Quarles — and by extension the Mueller probe itself — couldn’t objectively carry out the investigation.

While Trump and other Republicans have been complaining about the political interests of Mueller’s team, it’s actually against the law to consider political affiliations when making decisions about whom to hire, according to the FBI.

“Federal law and Department policy prohibit the use of political or ideological affiliations to assess applicants,” an FBI report on politicization at the agency released in 2008 found. PolitiFact did its own analysis of campaign contributions by the Mueller team, and while donations skewed heavily toward Democrats — $62,043 in total — Republicans did receive $2,750 from team members.

The weekend was profoundly unsettling; as Vox’s Ezra Klein has argued, “McCabe’s firing shows how Trump has corroded the operations of the American government.” It may get even worse in the coming days, especially if the president is winding up to try to remove Mueller.

Wright, the current law professor and former White House lawyer, told Vox he’s worried about what’s yet to come for one startling reason: “The president of the United States is unhinged.”