This browser does not support the Video element.
San Francisco - The defendant accused of killing Cash App founder Bob Lee testified in his own defense on Wednesday.
Nima Momeni took the stand in the murder trial for the first time about what happened, claiming during the long-anticipated testimony that he stabbed Lee in self-defense.
During cross-examination by prosecutors, there were plenty of prickly exchanges and objections by the defense.
While testifying, Momeni nervously laughed, saying public speaking was not his "forte" and that he was experiencing a range of emotions.
He became tearful, using a tissue to dab his eyes, as he recounted coming to the U.S. from Iran to escape his abusive father, along with his sister and mother.
Momeni testified he had no reason to be upset with Lee. He said the two were hanging out and the mood quickly changed. Momeni said Lee went from zero to 100 when he told the Cash App founder that he didn't want to go to a strip club.
Momeni said he told Lee, "If it was my last night in town, I'd go hang out with my family instead of f- around in strip clubs." Momeni acknowledged that was a "bad joke." "That set him off," he said.
On cross-examination, prosecutor Omid Talai asked Momeni, "Your story is that this prominent, beloved, respected man, he wanted to kill you over a dumb joke?"
"I don't know why the events took off like that," Momeni responded. He added his bad joke was one that Lee "took to heart."
Talai retorted, "Yes, he did take it to heart," referring to autopsy reports showing Lee died of stab wounds, including one that pierced his heart.
Demonstrating with his lawyer, Momeni alleged Lee attacked him with a knife under the Bay Bridge. He said he deflected the blows and Lee ended up getting stabbed in the chest.
Momeni said he threw the knife over a fence because he didn't want Lee to retrieve it. He testified that he casually walked away, having no idea Lee had been stabbed.
Authorities suggest Momeni was motivated by resentment after his sister, who suffered from drug addiction, was given too many drugs by Lee's alleged dealer, which led to a "bad trip" and her passing out.
Prosecutors argued that Momeni's version of events did not make sense.
KTVU legal analyst Michael Cardoza stressed the importance of the prosecution's cross-examination after the defense's positive portrayal of Momeni.
"When cross (examination) comes, as they say, the proof is in that pudding. How well will he do? How well will he answer the questions? Does he have believable answers or do they seem contrived?" said Cardoza.
Tim Oliver Lee, the victim's brother, was also in the courtroom.
"Just seeing him get angry and stuff on the stand, I feel like that's what my brother saw that night. Seeing him get angry. His story makes no sense to me and I don't think it makes sense to the jury either," he said.
Lee's brother shook his head in disgust as Momeni testified he was in complete shock and heartbroken when he learned that the Cash App founder had died. He said even though Lee attacked him, he didn't deserve to die.
Momeni will be back on the stand on Thursday for more cross-examination.
Henry Lee is a KTVU crime reporter. E-mail Henry at Henry.Lee@fox.com and follow him on Twitter @henrykleeKTVU and www.facebook.com/henrykleefan