SAN FRANCISCO (KRON) -- A contentious cross-examination between Bob Lee's accused killer and prosecutor Omid Talai escalated into several drama-packed moments at a high-profile murder trial this week. At one point, Talai told San Francisco jurors that his 8-year-old son could answer questions better on the stand than the defendant, Nima Momeni. Momeni testified for two full days trying to convince the jury that he killed the tech mogul on April 4, 2023 in self-defense. Talai scolded Momeni for cutting him off from speaking Thursday. When the defendant dodged questions, Talai raised his voice, repeated the same questions, and demanded answers. Momeni pointed his finger at Talai and said, "You are accusing me of something I didn't do. You're in my face trying to be argumentative." Bob Lee Superior Court Judge Alexandra Gordon had to intervene several times when Momeni, 40, became defiant and cross-examination spiraled with sparring. Bob Lee's brother, Timothy Lee, told reporters at the courthouse, "What you have seen is Nima being aggressive on the stand, you've seen him try to take control of this (courtroom), his arrogance and his entitlement are on full display here. This arrogant and entitled person is really just trying to make his deplorable actions and his reprehensible actions ... trying to revise them into something that will keep him out of prison." Prosecutors said Momeni murdered the Cash App founder under the Bay Bridge because he was enraged about Lee’s "inappropriate" relationship with Momeni’s younger sister, Khazar. Khazar previously testified that she was sexually assaulted by Lee’s drug dealer on April 3, 2023, the day before Lee was slain. Khazar Momeni walks out of a San Francisco courtroom with her mother on Oct. 22, 2024. (KRON4 Photo) Prosecutors said Lee was unarmed and he was stabbed through the heart by Khazar's "wannabe tough guy big brother." On the stand this week, Momeni told his side of the story. He said he was driving around in his BMW with Lee and they were having a good time. But the mood changed dramatically when Momeni made a "bad joke" about Lee spending time in strip clubs instead of with his family, the defendant testified. Momeni told jurors, "I said, 'If it was my last night in town, I’d go hang out with my family instead of f**king around in strip clubs.’ It set him off. He just blew up in front of me. He went from zero to one hundred." On Nov. 13, 2024 in a San Francisco courtroom, Nima Momeni and his defense attorney re-enacted as altercation between Momeni and Bob Lee. (Courtroom sketch by Vicki Behringer) Lee pulled out a knife and attacked, Momeni testified. "(Bob Lee) said, 'You think I'm a bad f**king dad? I'm going to f**k you up,'" according to Momeni. Lee, 43, was a divorced father of two. Timothy Lee said his brother was a kind person, an excellent father, close with his family, and would never turn violent if someone joked about his personal life. "The Momeni family trying to act morally superior here is ridiculous," the victim's brother said. Khazar Momeni ‘can go f**k herself,’ Bob Lee’s ex-wife says In front of the jury, Talai asked Momeni if he was trying to get away with murder. Talai said, "In the hours and days that go by, after you learn Bob is dead, and no one has been arrested, are you just hoping that you will get away with it?"  Momeni answered, "That's not true." Talai asked, "Are you thinking no one will figure out this little secret?" Momeni responded, "That's not what happened." A San Francisco Police Department SWAT team arrested the suspect on April 13, 2023 in Emeryville. Nima Momeni testifies on Nov. 13, 2024. (Courtroom sketch by Vicki Behringer) On Thursday, Momeni admitted that he never called police after Bob Lee was fatally stabbed. Talai asked, "Did you call the police?" Momeni answered, "No, I didn't."  Momeni said he called Khazar as he was driving away from the crime scene and told her, "Bob went crazy, don’t let Bob back in (her home). He just went crazy on me and attacked." Khazar (Photo by Justin Sullivan/ Getty Images) "Did you know Mr. Lee was fatally injured?" Zangeneh asked. "Absolutely not. He seemed normal as he walked away," Momeni answered. Lee left behind a heavy blood trail on Main Street as he called 911 and desperately tried to find help. Jurors listened to Lee’s 911 call and watched surveillance footage of Lee bleeding to death. Timothy Lee said Momeni lied through his teeth on the stand, and he's hopeful that jurors will see through it. https://twitter.com/AmyLarson25/status/1857219085593129451 Momeni claimed he didn't know Bob Lee died until April 5, 2023. The victim was admired and beloved in the Bay Area tech industry, prosecutors said, and he most recently worked as a chief product officer for cryptocurrency startup MobileCoin. In the days after the deadly stabbing, Momeni hired a criminal defense attorney and his family sold the BMW. Momeni said he sought help from an attorney because he knew Bob Lee was an icon in the tech world.