She's the woman at the center of a sensational murder trial, the other woman. A prominent utah doctor was found guilty of killing his wife but now all eyes are on his former mistress. Did he kill for... See More
She's the woman at the center of a sensational murder trial, the other woman. A prominent utah doctor was found guilty of killing his wife but now all eyes are on his former mistress. Did he kill for love? Dan abrams has the exclusive interview for our series, crime and punishment. We the jury, find the defendant as to count one, murder, guilty. martin McKneel convicted this weekend in a utah courtroom of murdering his wife in the couple's bathtub. The alleged motive? This woman, his long time girlfriend. I love martin. Do you still love him? I care for him on a very deep level. Today she sat down with us to explain her role in the bizarre murder trial of her former lover. PROSECUTORS ARGUED that McNeil convinced his wife to get a facelift so he could overprescribe medication and ultimately kill her all to start a new life with gypsy. To me he could have never done such a thing. But he loved you. And the allegation was that he loved you so much that he wanted his wife out of the picture so he could be with you. Martin had me any time he wanted me. I do not believe I was any kind of incentive. There are some who believe you were involved in planning THE MURDER OF michelle McNeil. You didn't know anything? I did not know anything. The jury reached its verdict after 11 hours of deliberation. If you will stand please. for McNeil's daughters, this was the moment they had been fighting for six and a half years to see. In fact, it was rachel and alex is' single minded determination that brought this case to trial at all and ultimately led to their once beloved father's conviction. Ever since the day my mom died I was concerned that my father killed her. I had been fighting to get justice for this case ever since then. She testified that shortly before her mother died, michelle SUSPECTED that McNeil was having an affair with gypsy. I know that woman. I know mom was worried you were having an affair with her and you're not to bring her into this home. How did he respond? He got irate. He was screaming at me saying how dare you, how dare you accuse me. Do you understand the animosity that his daughters feel towards you? I understand and I'm sorry for it. I was more selfish back then and truthfully I was living my life for me. Part of that life included MOVING INTO the McNeil home as the family nanny just over a week after michelle's death. I expected her to be focused on the children. I expected her to do things related to that, to cook or clean or take care of the children. And what did you see her doing? My dad was cooking. She was sitting there staring at my dad. It just was obvious that she is just goo eyes at my dad. Did you ever think to yourself, this would be a terrible idea for me to come in and be the family nanny? Yes, I did. It was a huge mistake and I'm so sorry. I only wanted to come and support the man that I cared for in whatever way I could. To this day, gypsy willis believes McNeil was innocent and was shocked by the verdict. It took me a little while to pull myself together. Why were you shocked? The martin I knew and loved was not the person that he was portrayed on the stands. To this day you don't believe that he killed michelle? I really don't. Attorneys argued that she collapsed while preparing the tub, not a murder at all. There is no evidence in this case that rises to the level of guilt beyond a reasonableable doubt. Once the daughters convinced the authorities to take a second look years later, they learned a LOT MORE ABOUT martin McNeil and michele's death. Is she conscious? Starting with the 911 call where McNeil claims he coulden help her. Prosecutors also presented EVIDENCE that McNeil pushed her doctor to prescribe more aggressive drugs and after her death asked a family friend to throw them all away. If you will come forward. But the prosecution's occasion always came back to McNEIL'S RELATIONSHIP WITH Gypsy. When did the two of you meet? In 2005, november. What attracted you to martin McNEIL IN THE FIRST PLACE? We started speaking on instant messager on the computer. He was very smart and funny and quick witted. And we had an immediate rapport. When you heard that michele McNEIL HAD DIED, DID ANY PART OF You think this is is a good thing? Now I can have him to myself? That was not my thought at that time. I was shocked and then I was concerned for his safety. And it wasn't smooth sailing for the couple. while McNeil was not initially arrested or even a suspect, his world started to crumble two years after his wife's death when he and gypsy were arrested for stealing the identity of martin's adopted ukrainian daughter and giving it to gypsy so she could escape paying off a massive death. Did you ever say you have got to be kidding me. You're telling me to take your daughter's identity? I did and I was uncomfortable with it. We had some arguments about it and it always came down to him saying to me, who knows better you or i? Both served time in federal prison and it wasn't until McNEIL WAS RELEASED THAT Prosecutors charged him for his wife's death. A woman gypsy told us she respected deeply. You said you had great RESPECT FOR michelle McNeil? Yes. But you were sleeping with her husband? I -- I have to say as time has gone on, I have had more and more respect for her. I think we probably had sex half the time. Gypsy was a star witness for the prosecution. I dressed in a dress. It was appropriate for the circumstance. McNEIL'S ATTORNEYS NOW SAY That gypsy willis made their case that much tougher. We wanted to get her off the stand as quickly as possible. Because we didn't want it to appear like she was covering or protecting martin. A legitimate concern since SHE SENT RACY TEXTS to McNeil the day before michelle's funeral. It's a little bit suggestive. It's showing your buttocks? Yes. I think I wanted to distract him. Also, I love this guy and i wanted to keep his attention. She did. And then even attended michelle's funeral. You wanted to go to the funeral of the woman whose husband you had been having an affair with? I was sorry. I was sorry that it was inappropriate. Despite those inappropriate choices, prosecutors did not charge her in connection with michelle's death and her lawyer doesn't expect that will happen. I believe if they had something there would have been two people at trial last month. While gypsy walked away a free woman, for his daughters, the guilty verdict against their father provided the justice they had long sought. McNEIL NOW FACES UP TO LIFE IN Prison. It's a whole web of lies. This was very well planned out and he almost got away with it. Knowing everything that you know now, are you sorry you ever MET martin McNeil? I truly cared for him. D I can't say that I'm sorry that I loved him, but I think everyone's life would have been better if I had not met him.
This transcript has been automatically generated and may not be 100% accurate.