Transcript for Convicted murderer Margaret Rudin maintains her innocence 20 years later: Part 1
We find the defendant guilty. Just out of prison after a 20-year sentence, Margaret Rudin sat down with "20/20" to tell her story and to talk about how she's still fighting to to clear her name. I am Margaret Rudin mason. I did not kill Ron. They zeroed in on me. She's been locked up for the past 20 years for the brutal beheading and murder of her millionaire husband Ron Rudin. They had no evidence. They had no witnesses. Margaret Rudin, dubbed the black widow of Las Vegas. Black widow. Black widow. They stuck the name on me -- black widow, black widow, black widow, like I had killed somebody before, or like that I was in the habit. I think that people don't know me. They don't try to know. Margaret Rudin is a chameleon. She's been a blonde, a brunette, a redhead. I like change. I'm a gemini. She's a chameleon, definitely. I like to wear wigs. I like short. I like long. I like curly. I like straight. I don't want to look the same way all the time. Even when I sit in front of your cameras, I may look different. But you're still going to know it's me. I'm Greg mullanax. I'm an attorney here in Fresno, California, and I represent Margaret Rudin. There are so many holes in this case. After going through all this stuff, considering everything, I'm convinced that Margaret Rudin's innocent. She was wrongly convicted. Even though it's circumstantial, all the evidence pointed to Margaret Rudin. I'm 100% convinced that Margaret was responsible for Ron's death. It was a mystery, which, quite truthfully, to this day hasn't been solved. What happened to Ron? We still don't know. 20 years later. They never checked on anyone but me. I want the truth to come out. I have waited a long time. This story really starts in Las Vegas in the 1960s. I have a feeling it's going to be a long show, boys. We're talking old school Vegas, where Frank Sinatra and the rat pack held court at the sands hotel and the mob's tentacles ran deep. Good old times. It was smooth. Everything was smooth. But underneath that river of calmness was a torrent. Vegas was cruel. The mob was real. They did run things. They would blow up your car. They would do whatever they had to do to make their point across so you knew, don't screw with us because we will kill you. It's pretty simple. It was into this risky, free-wheeling environment that 30-year-old Ron Rudin landed in Las Vegas in 1960, with big dreams of making his fortune in real estate. Ron saw great things that could transpire in Las Vegas back then. I love this picture. It's like he's looking at you, saying, hey, I'm Ron Rudin. I have a lot of plans for my future. He bought a strip mall. He had his office right there, but in the '80s and '90s when the explosion of construction hit in Las Vegas, that is when he started to make his real fortune. He watched Las Vegas just explode, and he was part of that with his real estate business. You could make a killing. That's exactly what Ron Rudin did. So, this is old Vegas. What was Ron's reputation like around these parts? Ron's reputation, he had a reputation of being a hard-nose businessman. Some people will say that Ron Rudin was unscrupulous, that it was anything at all costs to make money. He didn't like the glitz and the glitter. Ron Rudin wasn't a casino guy, but he absolutely made a name for himself in sin city. He was one of the characters here in Las Vegas. Ron would always wear cowboy boots, dressed all in black. Ron Rudin's style was a bit flashy, if you will. With flash comes those other undercurrents. The need for power, the need to be in charge, the need to be in control. He loved guns. He had a huge armory full of guns, all kinds of guns. Then he had the Cadillac. Yep. That's what he drove, the black Cadillac. He wasn't afraid to show off that he had made it. He knew he was on top of the pile. Women were attracted to Ron Rudin, and a lot of it was because of his lifestyle and his money, and he absolutely loved playing the love game. He had a twinkle. He was very handsome. Not just your average handsome. He really stood out. And when it came to his marriages, Ron went through wives like a casino dealer goes through packs of cards. Ron Rudin was married a total of five times, and each one of those marriages was its own story. Ron's first marriage in 1962 to wife Donna lasted less than a year. After about an eight-year hiatus, he gets hitched to his second wife, caralynne. While their marriage eventually failed, Ron kept a bracelet that she gave him with his name on it in diamonds, and he never took that thing off. Peggy was Ron's third wife, and this one appeared to be a happy marriage, but behind closed doors, Peggy suffered from severe depression, and that depression would manifest itself in the way of suicide. Peggy put a gun to her own head in the couple's bedroom. The gun that she used to kill herself with had Ron's fingerprints on it. It raised eyebrows. People thought maybe he killed Peggy. But there was a full investigation into her death, and it was in fact ruled a suicide. After getting married and splitting up for a fourth time, this time with wife Karen, just months after the divorce in September of 1987, a woman in church caught his eye. A pretty 42-year-old blonde named Margaret mason. Well, I had made a joke to one of my friends that went to our church. I had said to her, the very next husband I have is going to wear cowboy boots. Because in Vegas, that means they're macho. And I like macho. Yeah. That's her southern background. So, one day she said, there's a guy over there behind us that keeps looking at you, and he's wearing cowboy boots! Well, she was very smitten with him. I tell you, I've never met anybody better and slicker and smarter and suaver than he was. She just seemed like a really sweet person. And then I started hearing, you know, the other stuff. She didn't really realize what she had gotten into. One night he said to me quietly, what would you say if I told you I murdered Peggy?
This transcript has been automatically generated and may not be 100% accurate.