It started with a question. But, as it turned out, not even the right question.

Around the eight-hour mark of the January confirmation hearing of then-Sen. Jeff Sessions as attorney general, Sen. Al Franken (D-MN) drew attention to a just-published CNN blockbuster about an explosive dossier peddling outlandish allegations that the Russians had highly incriminating information about Donald Trump.

The dossier also contained less sensational but still-important allegations that Trump campaign associates had repeated contact with Russian intermediaries.

Franken pounced. Sort of.

“If there is any evidence that anyone affiliated with the Trump campaign communicated with the Russian government in the course of this campaign, what will you do?” Sen. Al Franken (D-MN) asked Sessions, still smiling and accommodating after a long day of grilling.

“I’m not aware of any of those activities,” an unperturbed Sessions said. And then, Sessions—a former federal prosecutor—went well beyond what Franken had asked.

“I have been called a surrogate at a time or two in that campaign and I did not have communications with the Russians, and I’m unable to comment on that,” Sessions replied.

The room did not buzz. Reporters did not scramble. But that seemingly innocuous response kicked off a chain of events that ultimately led to the appointment of a special counsel to oversee the sprawling federal investigation into Russia’s interference in the election and possible collusion by Trump campaign associates.

Recent revelations that President Donald Trump may have asked FBI Director James Comey to stop part of this investigation months before firing him accelerated calls for an independent probe.

But the roots were planted months earlier, with the exchange between Franken and Sessions in the Kennedy Caucus Room.

Less than two months later, after he was sworn in, Sessions’ team confirmed a Washington Post story reporting that in fact he had met twice with Russian ambassador Sergey Kislyak before the election when he was a top surrogate to the Trump campaign.

The revelation that he failed to disclose this under oath, or in a written question to the Senate about any 2016 contact he had with Kremlin officials, fueled bipartisan calls for him to recuse himself from any Justice Department investigations having to do with Russia interference in the election.

Those requests were granted that very afternoon, with Sessions announcing it was “right and just” for him to withdraw from overseeing any “matters that deal with the Trump campaign.”

With that move, the first senator to endorse Trump, one of his closest campaign advisers and the man who could have been the White House’s first line of defense was out of the game. Trump would have to weather the storm without a close confidant at the helm of the Justice Department.

Though Trump thought Sessions’ move unnecessary, acting deputy attorney general Dana Boente temporarily assumed control of the probe. He was succeeded by Deputy Attorney General Rod Rosenstein, a veteran federal prosecutor who was overwhelmingly confirmed by the Senate in a 94-6 vote in late April.

Though Democrats were disappointed that Rosenstein declined to commit to appointing a special counsel during his own confirmation hearing, his record in government and pledge to “ensure that every investigation is conducted independently” allowed Congress to breath a sigh of relief.

That moment of respite was shattered last week with Trump’s abrupt firing of Comey, which the administration initially pinned on a memo Rosenstein wrote criticizing the FBI director’s handling of the probe into Hillary Clinton’s email server.

Democratic senators branded Rosenstein a White House tool, with Minority Leader Chuck Schumer (D-NY) announcing from the Senate floor that “serious doubt has been cast on Mr. Rosenstein’s impartiality” and some even calling for his resignation if he failed to install a special counsel.

Reports circulated that Rosenstein was privately furious that he was being blamed for Comey’s firing, and he told senators in a closed-door meeting Thursday that he was asked to write it after Trump had already decided to let Comey go.

What felt like the 20th shoe dropped this week with a bombshell New York Times report alleging that Trump privately asked Comey in January to end a related investigation into fired national security adviser Michael Flynn, and that Comey documented the conversation in a memo.

Rosenstein announced Wednesday that out of the immense “public interest” in the investigation, he had named former FBI Director Robert Mueller as special counsel “in order for the American people to have full confidence in the outcome.” Mueller’s appointment was met with cheers across Washington, D.C., with the notable exception of the White House.

Like the President, the Attorney General was caught unawares by Rosenstein’s decision. By the time the two men were briefed, the order appointing Mueller was signed.