Transcript for Man found guilty at second trial for murder of ex-girlfriend's new boyfriend: Part 10
Amarillo doctor Michael Dixon is back on trial for capital murder. Thomas Dixon back in a Lubbock courtroom preparing for his second trial. Well today officials announce the start of the second trial. Everybody thought going into the first trial that prosecutors had a pretty rock solid case. Second trial, everybody was wondering what is the prosecution going to do this time around to make it so they get a conviction. Our strategy was basically we're going to let the facts do the talking. We're gonna show you what happened. We're gonnshow you the relationship between these two folks. And we're gonna convince you that Mike Dixon was running this show and that he orchestrated this whole thing. David Shepard had no reason to kill my dad, if it wasn't for Mike Dixon. In a retrial prosecutors can take any mistakes that they made in the first case, try to refine it, try to change it and present a often stronger case in the second trial. Clearly they were not going to take any chances with David Shepard's testimony this time. D lo and behold, who comes up but his daughter, who has information that could prove very damaging to Dr. Dixon's case. That was his chance to make it right with them and he threw it away. The number one most important thing from this second trial was the unbelievably courageous testimony of Haley Shepard. Haley Shepard testified and her testimony was extremely important in that fact that she basically described her dad for everybody. She told jurors that her father took herself and her two sisters out to dinner at a pretty decent steakhouse and had all sorts of gifts for them, and she found that very suspicious. He bought Haley a phone. He bought a new grill. He bought tires. He never had that much money ever. We all remember this same exact moment at dinner. We all asked him, "How do you have money?" And his words were, "I did some work for Mike." "Well, what'd you do?" He wouldn't tell us. "Don't worry about it. I just did some work for Mike. Don't worry about it." The Sonnier family has some hope that that testimony was the game changer that didn't exist in the first trial. The defense had its own star witness in Mike Dixon himself, but having the defendant testify is always a risk. It's a lot of times a defense attorney's nightmare. The prosecution sees that as red meat. Now the jury gets to hear from the man who's in the fight for his life and his freedom at this point. Our strategy was to show that there was a reason that Mike Dixon was asking David Shepard to be at Sonnier's house and to follow him. If the jury only has the text messages, without any explanation about what they were about, it's over. Mike needed to say, "I was wrong. I'm morally responsible. If I hadn't have asked David to get these pictures, maybe it wouldn't happen. I did not intend for Joseph Sonnier to die. I didn't ask Shepard to kill him." Part of the decision in whether to call a defendant to the witness stand is not just the substance of what he's going to say, but how is he going to say it? What's his demeanor like? Are the jurors going to like him or not? Those are all relevant factors. We learn from jurors that they didn't like Mike Dixon, not necessarily his testimony, they didn't like him. I thought he was his worst witness. I'll admit the longer he was on the stand the harder he was to believe. He had an ego that was larger than life. Anytime he starts talking about whether something is morally right or wrong I knew at that point I could not believe what he -- what he was testifying to. The jury, they seem to appreciate Haley's testimony. Shepard's daughter, that was tough to sit and watch her have to go through this. But they did what you would hope jurors would do. It wasn't one thing. They looked at all the evidence. And you could tell Dixon was running the show. I mean there was no doubt when you go through the evidence that he was -- as Mr. Powell stated, he was driving the school bus. This time around the jury did not take very long and there were no hold-outs. In just a handful of hours, they were back with a verdict. And my hand was shaking like this. The verdict is in. Unanimous verdict. Guilty on two charges. At first you're thinking I didn't hear that right. There's no way. It's not real. It's like a nightmare. I'm disappointed in the justice system. I always thought they were supposed to be the good guys. After a few minutes I had to turn to my wife and I had to say, "He -- he said guilty, right? He said guilty?" We've been waiting for that moment for over three years. I cried. I cried. I burst into tears. I was so relieved. When you look at the photos of him -- smug smile. When you look at his mugshot from his arrest -- smug smile. And it was so great to be able to know that we finally wiped that smile off his face. And I think he'll disappear into the prison system for the rest of his life. We'll never hear from him again. The jury's does its job. The prosecution wins, and there's at least some peace of mind, for the family of Dr. Sonnier, knowing that justice was served. Case closed? Not even close. Everyone was floored. I've always been amazed by what's next.
This transcript has been automatically generated and may not be 100% accurate.