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

mike dixon. >> really? mike. >> reporter: it was an unlikely bromance. dixon, a successful plastic surgeon, and shepard, a divorced unemployed con man. >> his money. and his success. >> dadanted to be mike. >> reporter: shepard may have been o obsessedith dixon, but dixon was obsessed with someone else. richelle shetina. >> he left his wifeor her. you know, she broke up his marriage. and he just wanted i guess paybyback. >> david shepard does come in and tells us exactly what happened. >> so he tells you everything. >> this whole thing was like this stair step, and it started at the very bottom of these stairs as being a prank. >> reporter: shepard tells police that it all began harmlessly enough, trying to tarnh dr. sonnier's reputation in the hope that richelle would to the arms of dixon. what were some of the things they came up with? >> they were going to get this porn subscription, like child gay important, and they were going to send it to dr. sonnier's office. >> go to an adu bookstore and buy the mostt obscene, nastiest, man-boy love association b

mike dixon. dance of death. >> there's a bullet. i need somebody to hurry. >> there are police cars everywhere. there's crime scene tape all around. it was just absolute chaos. >> it was an in and out job, a hit to kill this person specifically. >> reporter: tonight only on "20/20," the woman caught in the middle between two doctors. >> the kind of plot you expect from a soap opera. >> this is the oldest story in the book. this is vengeance. this is revenge. this is pride. >> reporter: a dangerous game of cat and mouse. >> accused of hiring a hit man -- >> so there was some kind of a triangle things going on. >> reporter: but who's the cat? >> no part of this is right. >> reporter: who's the mouse? >> this is a huge whodunit. >> reporter: a case with no shortage of suspects. a list of ex-girlfriends. a peeping tom in the back yard. and a con man with his own obsession. >> i'm kind of a sassy smart [ bleep ] and we just kind of hit it off. >> reporter: characters so villainous even their own >> yo

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 like a likely suspect, but he has an alibi the night of sonnier's murder. dete

mike dixon. >> reporter: well known, he's divorced and wealthy. year and a half before she broke up. >> he knew thafes dating jason. he cald him b name in a series of text messagages. he wanted me to come back to him. i told him no. >> reporter: but is dixon the kind of man to t take n for an answer? johnson wants to find t. soe drives two hours to amarillo for a face-to-face conversation with rashel's ex, records. >> dr. dixoxon, i'm with the lubbock police department. >> his first thing was, oh, my, i don't know anything abouthim. >> 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 love, love, loved that woman.n. bells were sounding. >> reporter: dixon seems like a likely suspect, but he has an alibi the night of sonar's 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 laying on the floor, not moving, n

. >> mike dixon never wanted that to happen. >> reporter: days afterwards shepherd confesses. >> i check his pulse in his neck. >> reporter: implicating his buddy. >> he wanted him hurt and then it gradually developed into having him killed. >> reporter: shepard saying dixon paid him three bars of silver and a box of cubans for the hit. the monk of his funeral dixon arrested charged with capital murder. shetina says she'll never forget that phone call. >> my knees literally collapsed and i just kind of sank to the floor. and i cried and i screamed. >> reporter: last november dixon is found guilty on two counts of capital murder. his attorneys still maintain his innocence. but shetina says this case provides an important lesson. >> there are real sociopaths and psychopaths that walk amongst us. >> reporter: now dixon's lawyers and his son tell us that shepard acted alone. their client never ordered the hit. his lawyers are appealing this verdict and as for his buddy shepard he is in prison for life. for the first time his daughters exclusively to us not only do they fully support the vict