He raised his voice and acted out scenarios in dramatic fashion. He snapped as she dodged questions, cutting her off mid-sentence. Arias held her own periodically, appearing to smugly toy with Martinez as she smirked and repeatedly answered yes or no questions with "sure" and "I guess."
The exchanges rattled the seasoned prosecutor as the case at times devolved into a showdown of wit and will. The judge had to admonish both to stop speaking over each other.
"I think I'm more focused on your posture and your tone and your anger so it's hard to process the questions," Arias told Martinez.
The exchanges came during a pivotal week of testimony in the case and raised questions among the thousands of trial watchers around the world about whether the prosecutor's ferocious approach helped or hurt his chances of landing a first-degree murder conviction and securing a death sentence.
Some experts say the approach could undermine the prosecution's case, diverting attention from the brutal attack and putting the spotlight on him. Others compliment his tenacity as a no-nonsense tactic aimed at stumping Arias and getting her off script after having several years in jail to rehearse her testimony.
As Martinez noted in his January opening statements, this case isn't a whodunit. Arias admits to having killed her lover in his suburban Phoenix home in June 2008, she says, in self-defense. Authorities say she planned the attack on Travis Alexander in a jealous rage, then repeatedly lied to friends, family and police to cover her tracks and avoid suspicion. Arias admits to the latter, too, noting she was too ashamed and scared to tell the truth, first denying having anything to do with it, then blaming it on masked intruders before settling on self-defense.
It's a prosecutor's dream case largely based on Arias' own actions and repeated lies. She dumped the gun in the desert, got rid of her bloody clothes, tried to clean the scene at Alexander's home and even left the victim a voicemail on his mobile phone within hours of killing him and dragging his body into the shower.
And while most observers agree she will likely be convicted of first-degree murder—at the very least the lesser second-degree—some say it will be due to Arias' own missteps, not Martinez's prowess as a prosecutor.
"And if the jury comes back with death, it won't be because of Juan Martinez. It will be in spite of him," said Phoenix defense attorney Mel McDonald, a former Maricopa County judge and federal prosecutor.
McDonald, who has seen Martinez in action for years, said his style has always been combative.
"You can be mad, but to be mad all the time is strategically not well-reasoned," McDonald continued.
Of Martinez's performance on cross-examination last week, he said, "It was like two people having an argument, and when that happens, it takes the focus away from Jodi Arias and this absolutely grotesque human act of sheer brutality where it belongs."
Alexander had been stabbed and slashed 27 times, had his throat slit and was shot in the forehead.
McDonald noted Martinez's style "makes for great television, nice theatrics, but for effective litigation, it simply isn't the way to do it."
The trial has captured headlines nationwide for weeks with salacious tales of raunchy sex, betrayal and a bloody killing, and is likely one of the most high-profile cases ever handled by Martinez, who has been a county prosecutor here for 25 years, the last 17 solely focused on defendants charged with murder. He has declined to comment during the trial.
California criminal defense attorney Michael Cardoza, who has been following the case, said that while Martinez's approach may have turned off some jurors who see a fragile woman on the witness stand, regardless of the heinous nature of the killing, his toned-down style on his final day of questioning Arias on Thursday sealed the deal.
"That was the best day he had. That was the case for him, that was absolutely the case," Cardoza said.
Cardoza also noted that Martinez may have been aggressive by design to wear down her preparedness and catch her off-guard.
"When the defendant gets in trouble is when they get comfortable, and that's when you know you've got them, that's when you start peppering them," he said. "They think they're smarter than you."
As defense attorneys question Arias again on Monday, Cardoza said their main goal will be to "blunt the sting" of the cross-examination, during which she admitted to lying repeatedly trying not to get caught.
As she described her efforts to avoid suspicion, Arias buried her face in her hands and sobbed. Martinez continued to press her. He later turned to the judge and simply said "I don't have anything else," then unassumingly returned to his chair.