dr. mike dixon. >> hello. i'm dr. mike dixon. if you're considering plastic surgery -- >> reporter: well known, he's divorced, wealthy, and used to date richelle. >> he had a place in amarillo and i went there to get botox injections. >> what attracted you to him? >> he was funny, he was very witty, and he was enjoyable. if it can be enjoyable to have somebody put needles in your face, you know, i guess that's be. >> reporter: richelle and dr. dixon had dated for a year and a half before they broke up and she started seeing dr. sonnier. >> did he know about your current relationship? joseph. he called him by name in a series of text messages, trying to get me to go out with him and to meet him for coffee. >> reporter: richelle says she rejected his advances but he was >> so he wanted you to see him on the side, basically? >> he wanted me to come back to him. i told him no. >> reporter: but is dixon the kind of man to take no for an answer? johnson wants to find out. so he drives two hours to amarillo for a face-to-face conversati

hard-charging texas district attorney named matt powell. >> mike dixon's running the show >> many people make thee dixon never laid a hand on dr. sonnier. >> he's just controlling the -- dave shepard's just another instrument for mike dixon.hat instrument dave shepard has agreed to testify. pitted against his friend mike dixon to avoid the death penalty. >> this is the oldest story in the book. this is vengeance. this is revenge. >> reporter: the motive? in courtroom 72 of the lubbock county courthouse the prosecution paints a picture for the jury of dixon as anulating puppetmaster. >> he wanted her to suffer or he wanted her back. he knows what the true answer to that question is. but dr. sonnier was in the way. >> reporter: the pillars of e -- police find the gun shepard used at the bottom of a lake, conveniently located behind dixon's office. and discover it's registered to dixon's brother. and theynce videos from the day after the murder. that's shepard in the plaid the two hanging out.s. >> was there any discussion about when the police went over there and spoke to him? >> he was nervous. he said i had to get out of town.

dr. michael dixon. heaz a plastic surgeon in amarillo. >> hello, i'm dr. mike dixon. >> reporter: well known, he's divorced and wealthy. rachelle and dr. dixon dated for a year and a half before she started seeing dr. sonnier. >> he knew that i was dating joseph. he called him by name in a series of text messages. he wanted me to come back to him. i told him "no." >> reporter: but is dixon the kind of man to take "no" for an answer? johnson wants to find out. so he drives two hours to amarillo for a face-to-face that detective johnson secretly records. >> dr. dixon, i'm detective johnson with the lubbock police department. >> i told him rachelle's boyfriend and his first thing was, oh, my, i don't know anything about him. >> i haven't talked to her in months and months. >> okay, well, that's a little odd, because she told us that he knew about the relationship. >> i'll be honest with you, i love, love, loved that woman. i really did. >> reporter: for detective johnson, alarm bells were sounding. in fact, made a lot of changes for her. >> reporter: dixon seems l

dr. michael dixon. >> hello, i'm dr. mike dixon. divorced and wealthy. rashel and dr. dixon dated for a year and a half before she broke up. >> he knew thafes dating jason. he called him by name in a series of text messages. he wanted me to come back to him. i told him no. >> reporter: but is dixon the kind of man to take no for an answer? johnson wants to find out. so he drives two hours to amarillo for a face-to-face conversation with rashel's ex, that detective johnson secretly records. >> dr. dixon, i'm with the lubbock police department. >> his first thing was, oh, my, i don't know anything about him. >> i haven't talked to her in months and months. >> okay, well, that's a little accounted, because she told us that he knew about the relationship. >> i'll be honest with you, i >> for detective johnson, alarm bells bells were sounding. >> reporter: dixon seems like a likely suspect, but he has an murder. >> there's something not right here, this is a huge whodunnit. until a witness comes forward with a name, dave shepherd, who soon confesses to the crime. >> he's lay

. >> mike dixon's running the show >> many people make the argument that mike dixon never laid a hand on dr. sonnier. >> he's just controlling the -- dave shepard's just another instrument for mike dixon.