Here are the key moments from the hearing.
1. The contempt threat
It didn't take long for the hearing to explode. After the opening statements, House Oversight Committee Chairman Trey Gowdy (R-S.C.) lodged his first question: How many people did Strzok interview during the first eight days of the FBI's Russia investigation, between July 31 and Aug. 8, 2016?
Strzok, as he previewed in his opening statement, said he had been advised by the FBI's lawyers that he was not to address specifics of what is still an ongoing investigation. (The investigation was handed over to special counsel Robert S. Mueller III in mid-2017.) Republicans quickly objected and threatened to hold Strzok in contempt. Democrats noted that it was unusual that Strzok be asked to disclose such details in a public setting.
Strzok said he didn't have to answer the question because, despite being subpoenaed by the committee, he had previously said he would speak voluntarily.
“Mr. Chairman, I do not believe I am here under subpoena,” Strzok said. “I believe I am here voluntarily. … Based on that, I will not answer that question.”
Democrats argued that a witness such as Strzok would not be expected to publicly disclose sensitive information like the blueprint for a hydrogen bomb. Another moved to adjourn the hearing less than an hour after it began.
House Judiciary Committee Chairman Robert Goodlatte (R-Va.) finally said that Strzok would be recalled to the committee after the day's hearing so that it could determine whether to hold him in contempt. But the tone was set.
2. Strzok's angry retort: 'It is deeply destructive'
After more than 20 minutes of maneuvering and posturing following the subpoena discussion, Gowdy ended his interrogation of Strzok and Strzok was given the floor to respond. In a minutes-long retort, he called Gowdy's and his Republican allies' allegations of bias and improper actions “deeply destructive.”
He said that his text messages critical of Trump shortly after the investigation began were in response to Trump's behavior on the campaign trail — and not a reflection of his investigative intent. He pointed in particular to Trump's attacks on the Khans, a Gold Star family who spoke at the Democratic National Convention around that time.
“My presumption [was] based on that horrible, disgusting behavior that the American population would not elect somebody demonstrating that behavior to be president of the United States,” he said. “It was in no way, unequivocally, any suggestion that me, the FBI, would take any action whatsoever to improperly impact the electoral process for any candidate. So I take great offense . . . ”
Strzok concluded the accusation against him and the line of questioning “deeply corrodes what the FBI is in American society, the effectiveness of their mission, and it is deeply destructive.” Some in the room applauded.
3. A perjury accusation — and a very personal attack
Rep. Louie Gohmert (R-Tex.) seized upon Strzok's contention that his texts didn't demonstrate personal “bias” and said that argument amounted to him lying. When Democrats noted that Gohmert was basically accusing Strzok of perjury — given he made that claim under oath — Gohmert was unbowed.
Then he got personal — very personal.
“When I see you looking with a little smirk, I wonder how many times did you look so innocently into your wife's eyes and lie to her about Lisa Page,” Gohmert began. The hearing room erupted, with someone shouting “insane asylum” and someone else asserting that Gohmert needed medication.
In response, Strzok acknowledged “hurting” someone he described as a “family member.”
“The fact that you would question whether or not that was the sort of look,” he told Gohmert, “goes more to a discussion about your character.”
4. The transcript threat
One of the subplots here has been Democrats' push to release the transcript of Strzok's previous, closed-door testimony. They argue that it has been selectively leaked and described to impugn him.
So at one point early in the hearing, Rep. David N. Cicilline (D-R.I.) said he intended to release the transcript himself — and asked whether there was any reason he couldn't. Goodlatte stressed that it was the committee's practice and that there was an agreement to keep closed-door hearings private while an investigation is ongoing.
Cicilline's response: “We intend to release this transcript unless someone presents some rule that prevents us from doing it, and we’ll give you till 5 this afternoon to present that,” he said. “Otherwise we intend to release the transcript.”
Eventually Cicilline got some backup from GOP Rep. Mark Meadows (N.C.), who happens to be the head of the conservative House Freedom Caucus.
It's worth noting that Goodlatte's justification — that the committee's investigation is ongoing — was the same one Strzok offered for not answering questions about the special counsel's Russia probe. In the latter case, apparently, Republicans don't think it applies.
5. Making him read his own texts
Rep. Darrell Issa (R-Calif.) took his five minutes to force Strzok to read some of his own texts — including ones that used vulgarities.
While reading one in which he used the f-word while talking about Trump, Strzok paused and asked how he should handle it, then finished. Then Issa asked him to read it again.
“Sir, was that not intelligible?” Strzok said. “You just want to hear — for me to repeat it.”
“Please,” Issa said.
“Okay, sir. Sure,” Strzok shot back snidely. “Happy to indulge you.”
6. A Democrat says Strzok should get a Purple Heart
The difference between the lines of questioning between Republicans and Democrats was, as usual, stark. While Republicans badgered Strzok and tried to catch him off-guard, Democrats mostly used their time to argue for the importance of the Mueller investigation.
But some Democrats decided to go further than that and to make Strzok a martyr — or even a hero. Rep. Steve Cohen (D-Tenn.) went the furthest.
“Mr. Strzok, if I could give you a Purple Heart, I would,” Cohen said when he began his questioning.
To recap, Strzok was removed from the Mueller investigation and harshly criticized by an inspector general. It is generally agreed that his text messages were problematic, regardless of if you think this reflects corruption and bias in all law enforcement or the Mueller probe.
7. 'This is not Benghazi'
Democratic patience with the GOP's treatment of Strzok quickly wore thin. Gowdy, in his role as head of the Oversight Committee, repeatedly afforded himself the chance to try to get under Strzok's skin.
And toward the end of the hearing, the whole thing boiled over. Rep. Bonnie Watson Coleman (D-N.J.) yelled at Gowdy during one interrogation of Strzok, telling him to "leave it alone."
"This is not Benghazi," she said, referring to the years-long investigation Gowdy led into the deaths of four Americans in Benghazi, Libya, which Democrats contend that probe devolved into a witch hunt against Hillary Clinton.