But first the California man on trial for killing a man over their yards. He claims self-defense. Matt Gutman is following the case. Reporter: In an argument over shubry. Cutting trees. Reporter:... See More
But first the California man on trial for killing a man over their yards. He claims self-defense. Matt Gutman is following the case. Reporter: In an argument over shubry. Cutting trees. Reporter: Turned this economist, Michael vilkin, into a dirty harry. I saw a pistol in his right hand. It was like one second. And I pulled out my revolver and shot him. Reporter: Not any revolver, but the .44 magnum immortalized. Upton was cut down in 2013, and he died instantly. And he's on trial for first degree murder. Claiming self-defense. Featured on 20/20 in the 90s, rescuing deformed orphans, he was a hero to so many. Including his girlfriend who we interviewed days after the shooting. What could I say? Reporter: He never did build in this neighborhood, he tended it lovingly. He called it obsessive. None was permitted. It was a landslide property. It doesn't safe for the neighbors. Reporter: He was called out on it, he told jurors Upton was a bully. They said he brought the handgun with blood, not bushes on his mind. He went out to call a truce. The dream home. No, it's all good. It's all good. We're out of here. Reporter: Those were allegedly among Upton's last words. For "Good morning America," Matt Gutman, Miami. Let's talk about this with Dan Abrams. How does this look? Not a strong self-defense case. You have an eyewitness who contradicts the testimony of the defendant. No one backing up his account other than his own testimony. With that said, remember, the prosecution, even in a self-defense case in California, has the burden to prove, in effect, that it wasn't self-defense. Key elements of self-defense, was it reasonable to believe that? And was it necessary to do what he did? And, you know, I think that that's a tough argument for him to make. The prosecutors have the burden. But it's why he had to take the stand with the vivid testimony. Without his testimony, there was nothing to support his claim of self-defense. And still evidence on the other side to indicate that it wasn't. So I think it was absolutely crucial that he took the stand in this case. And that means whether the jurors believe him is the key. How does him being a humanitarian play into this? It doesn't right now. What happened at that moment, whether it was or wasn't self-defense, whether or not he was a humanitarian is not important. It could come up in sentencing. And now to a quick-thinking girl who used Facebook to save
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