Arizona prosecutor Rachel Mitchell questions Christine Blasey Ford as she testifies before the Senate Judiciary Committee on Thursday. (Melina Mara/The Washington Post)

For five minutes at a time, as she was quizzed by a prosecutor about the details of an alleged assault that occurred when she was 15 years old, Christine Blasey Ford was on trial.

And then, for five minutes, she wasn’t.

The Republican decision to relinquish each GOP senator’s five minutes of question time to a career sex-crimes prosecutor turned Thursday’s hearing on Ford’s accusation against Supreme Court nominee Brett M. Kavanaugh into a strange hybrid: part legal deposition, part therapy session.

Throughout the morning, Ford swiveled abruptly between Arizona prosecutor Rachel Mitchell, who focused on the minutiae of her account, and Democratic senators, who worked to elicit the emotional impact of the alleged assault.

“This is utterly bizarre,” said Peter Zeidenberg, who was a veteran prosecutor in the Justice Department’s public integrity section, as he watched the session unfold. “This is no way to conduct an investigation, on live television in five-minute increments. It’s ridiculous and offensive.

The dueling approaches were mirrored in the reactions outside Congress. Ford was lauded by supporters on social media as a hero, while some Kavanaugh advocates focused on small details raised by Mitchell — such as Ford’s decision to fly to Washington, even though she said the alleged attack gave her a fear of enclosed spaces.

President Trump’s son Donald Trump Jr. tweeted, “I’m no psychology professor but it does seem weird to me that someone could have a selective fear of flying.”

When Kavanaugh testified later in the day, Mitchell was largely sidelined as the Republican senators took to their microphones and denounced how Democrats had handled Ford’s charges.

“Frankly, I think there was some frustration among the senators that they thought there were arguments that needed to be made, that she frankly was not equipped to make,” Sen. John Cornyn of Texas said after the hearing.

Mitchell was left sitting quietly, her hands folded — creating the odd dynamic of a prosecutor hired to probe the credibility of the accuser but not of the accused.

The Maricopa County prosecutor never laid out a broad theory in her questions to Ford. Instead, she asked Ford to mark her home on a map of the Chevy Chase area. She asked her to review each of her past statements about the attack and explore whether her account has been consistent over time. She inquired whether Ford was on medication the night she remembered that Kavanaugh and friend Mark Judge locked her in a bedroom and attacked her. (“Not at all,” Ford recalled.)

Speaking calmly, Mitchell laid out questions that built on one another in a rhythm familiar to anyone who has witnessed a courtroom trial. But each time Mitchell began to get some momentum with her questioning, her time would end and the floor was turned over to a Democratic senator.

For their part, the Democrats took turns empathizing with Ford and reassuring her that they believed her.

Sen. Patrick J. Leahy (Vt.) asked Ford what memory she could not forget from the assault. “The laughter,” she said.

Sen. Richard Blumenthal (Conn.) praised her for providing the country “an incredible teaching moment.”

“You are not on trial,” Sen. Kamala D. Harris (Calif.), a former prosecutor, told the witness.

Republican had selected the format, eager to avoid the image of Ford being interrogated by 11 male GOP senators.

But the decision left Judiciary Committee Chairman Charles E. Grassley (R-Iowa) as largely the only member of his party whose voice was heard during Ford’s testimony. From time to time, he interrupted the proceedings to sternly defend his handling of the allegations and decision not to allow other witnesses to testify.

By the afternoon, some Republicans appeared to be regretting the format.

Sen. Ron Johnson (R-Wis.) told reporters that he had believed Mitchell would be afforded larger blocks of time to provide “more continuity in the questioning.”

“When you chop up the questioning, it just is hard to develop a really good line to really get to the heart of the matter, so that’s unfortunate,” he said.

Conservative commentator Byron York, who has been supportive of Kavanaugh’s confirmation, wrote in a tweet, “To put it mildly, this hearing isn’t working for GOP. Dems are asking big, meaningful questions. What do you remember? What did you feel? Could it have been anyone else? Getting big, meaningful answers. GOP’s Mitchell focusing on little stuff. Huge contrast.”

When Kavanaugh testified in the afternoon, Mitchell began methodically pressing him about his drinking habits and notations on his 1982 calendar.

But Republicans soon seized back their time. In a thundering speech, Sen. Lindsey O. Graham (R-S.C.) called the late-breaking allegations “the most unethical sham” he’d seen during his time in the Senate.

A registered Republican, Mitchell, 50, is described by colleagues as a professional and diligent prosecutor. She has specialized in sex crimes since joining the Maricopa County Attorney’s Office in 1993.

She chose to focus much of her inquiry not on Ford’s memories of the attack but instead on her interactions with Democrats and The Washington Post as she weighed whether to come forward publicly.

Nick Akerman, a former Watergate special prosecutor, said he thought Mitchell’s lines of inquiries made sense as a way of carefully exploring whether Ford was motivated to lie or had a vendetta.

“She’s doing what you would expect someone who does this sort of thing for a living does — trying to figure out whether there are any inconstancies, trying to get explanations for things that people may be worried about,” he said.

In the face of Mitchell’s questioning, he said, Ford had come across as “very straightforward and credible.”

“I just don’t see how any of it helped Republicans — other than keeping them out of campaign commercials,” he said.

Conservative writer Erick Erickson, a vocal Kavanaugh supporter, wrote on Twitter that Mitchell had done a good job drawing out facts that can be used to try to persuade Republicans on the fence that her testimony had been manipulated by Democrats. He noted that Ford had acknowledged to Mitchell that one of her lawyers had been recommended by Sen. Dianne Feinstein (D-Calif.) and that her lawyer had paid for her polygraph test.

“We get all that because Mitchell focused on process,” he wrote.

As she concluded her questioning of Ford, Mitchell seemed to acknowledge the constraints she had been under. She asked Ford whether it would surprise her as a research psychologist that “this setting in five-minute increments is not the best way to do it.”

“No,” Ford answered.

“The best way is to have an interview one on one in a private setting and to let you do the talking,” Mitchell said.

And with that, like in any courtroom examination, the prosecutor concluded: “I have no further questions.”

Sean Sullivan, Seung Min Kim, Ann E. Marimow and Erica Werner contributed to this report.