narrator: investigators can search years for a clue to crack a case wide open. some get a lucky break from out of nowhere. and that's what happened to detective zach johnson in the joe sonnier murder investigation. interviewer: you said yourself someone always knows somebody.

somebody always knows something. and there was your someone. and there was our someone that came forward with the information. narrator: that someone was a guy named paul reynolds. he told detectives his friend confessed to killing a doctor in lubbock. and who was his friend? he was a man police learned about the first night of their investigation. his name was dave shepard. what does your jaw do when you hear the name david shepard. oh, i couldn't believe it. and i was like, i think we got him. i think we've got good information. nobody knows this. narrator: and reynolds had more for the detective.

narrator: a girlfriend, two doctors, a love triangle? guess who was also involved? someone the detective already knew, dr. mike dixon. dixon, remember, dated richelle before she met joe sonnier. they were the doctors in that love triangle. narrator: reynolds then made a vague, but ominous connection between dr. sonnier and dixon. narrator: the detective, you'll recall, talked to dixon hours after joe sonnier was found murdered.

narrator: johnson had been suspicious of him from the start. your spidey sense was going off. yes, yes. there were a lot of issues here that happened during this time with him. but i don't have any probable cause to go and investigate this man any further. narrator: for instance, that night, when the detective interviewed dixon, he didn't mention that shepard had dropped by to pick up those cigars. that information came from dixon's girlfriend. and he acted strange when asked about it. and he stood very still. and then he collected himself, and we're back to the, "oh, well, his name is dave shepard. why do you need to know about him? narrator: now that answer made sense. zach johnson: because he knows that david shepard is involved in the murder, and he doesn't want me to link on to dave shepard and to talk to him. narrator: and there was another part of reynold's

story that added a critical detail to something police had already learned. he said shepard had been stalking joe sonnier. narrator: detective johnson thought back to that flash richelle said she and joe saw one night at his house. narrator: and earlier that same day, she saw someone watching her in the parking lot outside her gym. narrator: dave shepard was a big guy, well over 6 feet tall and some 300 pounds. so it could have been him. even at night, i could see the man inside the car. narrator: and it wasn't just richelle who thought someone was watching her. debra hollowell, the dance instructor, told investigators she noticed a stranger watching her studio from a parking lot across the street.

debra hollowell: right around that area over there. narrator: it was the studio where richelle and dr. sonnier went dancing. woman: i would see him outside quite often when i would take my smoke breaks, hiding behind a semi truck. i felt like he was just really staring over in our direction. narrator: her description could fit shepard as well. she said he was big and shaggy. he was just staring. and that gave me such a bad feeling. narrator: there was yet another detail reynolds had for the detectives, the handsome reward shepard said dixon offered him to kill dr. sonnier. dixon gives him a silver bar as an advance, and he gives it to him around father's day. detective (over phone): this bar of silver--

narrator: sheriff's deputies were monitoring the interview as it happened. zach johnson: well, one of those deputies gets on a computer database, types in david shepard's information, and there you go. there's a silver bar that david shepard sold in amarillo, texas, around father's day. we have it confirmed. narrator: police were convinced they had their suspects. hours later, a swat team showed up at mike dixon's house. how shocked was he? he was he was very shocked. he was very angry. narrator: it was 2:00 in the morning when they brought him in for questioning. interviewer: did he start talking at all, or was he still shut down? he requested his attorney.

narrator: shepard wouldn't talk either. narrator: police notified the sonnier family hours later. it was the day of joe's funeral. they told me that they had arrested david shepard and mike dixon for my dad's murder. so it made the funeral slightly easier for us as a family because justice was on its way. what did you know about michael dixon and dave shepard, leading into that arrest? how much did you know. we knew absolutely nothing about them other than thomas michael dixon had dated richelle before my father. that is it. narrator: they soon would learn plenty about a twisted and devious plan that led to joe sonnier's murder. [music playing] coming up, double trouble from a very odd couple-- dr. dixon was very well educated. he had a successful business up in amarillo. david shepard, he was a con man.

his life was just tanking. narrator: --when "dateline" continues. [music playing] do your dry eyes still feel gritty, rough, or tired? with miebo, eyes can feel ♪ miebo ohh yeah ♪ miebo is the only prescription dry eye drop that forms a protective layer for the number one cause of dry eye: too much tear evaporation. for relief that's ♪ miebo ohh yeah ♪ remove contact lenses before using miebo. wait at least 30 minutes before putting them back in. eye redness and blurred vision may occur. what does treating dry eye differently feel like? ♪ miebo ohh yeah ♪ for relief that feels ♪ miebo ohh yeah ♪ ask your eye doctor about prescription miebo. hi. i use febreze fade defy plug. and i use this. febreze has a microchip to control scent release

so it smells first-day fresh for 50 days. 50 days!? and its refill reminder light means i'll never miss a day of freshness. ♪

craig here pays too much for verizon wireless. so he sublet half his real estate office... means i'll never miss a day of freshness. [ bird squawks loudly ] to a pet shop. meg's moving company uses t-mobile. so she scaled down her fleet to save money. and don's paying so much for at&t, he's been waiting to update his equipment! there's a smarter way to save. comcast business mobile. you could save up to an incredible 70% on your wireless bill. so you don't have to compromise. powering smarter savings. powering possibilities.

♪ you gotta give the people ♪ ♪ you gotta give the people ♪ ♪ you gotta give the people ♪ ♪ what they want ♪ wait till you see this. five days after joe sonnier's body was found, police arrested mike dixon and dave shepard for his murder, and detective johnson began looking into their backgrounds as he built a case against them. by all accounts, the two appeared to be an unlikely duo.

what were you learning about dr. mike dixon? dr. dixon was very well educated. he had a successful business up in amarillo. he was probably the best hand surgeon between amarillo and dallas. he was extremely motivated in what he wanted to do. and he worked my whole life to build what he ended up creating, was his practice. narrator: andrew dixon is mike dixon's son. woman: he was a fantastic plastic surgeon. he kind of taught me, once you see something, no matter how hard it is, no matter how hard you have to work, you can get it. you can achieve those things. narrator: and he set an example for his son. andrew says his dad worked tirelessly to build his successful practice. it also included cosmetic services. at one point, he even had his own talk show. his patients loved him. narrator: not just for the way dixon made them look, he says, but how he treated them, too. andrew dixon: if people couldn't afford things or needed help, he was there to help them.

and i remember at thanksgiving, we would always load up food and go to his patients that didn't have a lot of family. so we would come in and bring them food and talk with them for a little while. and i mean, he was there for them, and he cared about them. narrator: then there was dave shepard, big dave, as he was known, the polar opposite of high-achieving and charitable mike dixon. interviewer: who was this man? what did he do? what was his story. david shepard, he was a con man, is what we came to learn about him. he had tried several business ventures for himself, anywhere from real estate to pharmaceutical sales. personally, his life was just tanking. as soon as he came into money, he got rid of it. he spent it. narrator: in his interview with the detective, paul reynolds said he'd known shepard since they were teenagers.

narrator: big dave was known for the tall tales he told. was he full of you know what? yes. narrator: he bragged about jobs he never had. interviewer: let's run down some of the occupations that he's claimed to have. ok, private investigator is what he claimed to be at one time. true or false? i believe that to be false. sheriff's deputy. i believe it was potter county. he even had a badge in his possession. interviewer: true or false? zach johnson: that was false. he claimed to be a very successful businessman in every business venture that he had. narrator: that was false as well. zach johnson: he was a person that liked to put on a facade that, hey, i'm on the up and up. narrator: instead, he was down and out. but that didn't stop him from living large. he spent time at cigar shops, strip clubs, and martini bars. detective johnson learned more about him from one of his bar buddies.

narrator: so what brought the deadbeat and the doctor together? the two enjoyed fine cigars and saw each other occasionally at smoke shops in amarillo. they became friends around 2010, when they both went through divorces. zach johnson: and they kind of bonded over that poor misfortune, i guess. narrator: shepard's bar buddy told the detective he heard shepard rave about dixon. narrator: the two friends became business

partners in 2011, when shepard had another one of his big ideas. in his interview, reynolds said he was in on it briefly as well. narrator: andrew dixon remembers meeting shepard twice, once in a restaurant with his dad when they told him about that new business idea. andrew dixon: didn't seem anything too off by the guy. but i didn't really have a lot of communication with him. i didn't have a lot of time to spend around him, so i couldn't really formulate a good opinion about him. narrator: another time was when his dad invited shepard for thanksgiving. andrew dixon: and he told me that david was going through a rough time. and at the time, i knew my mom and dad were kind of going through a rough time, too. so i think they were going through things together at the same time, to where they could kind of feel for one another. and that's what he told me. he said, david's going through a hard time, so he's coming to thanksgiving. narrator: but now his father and shepard were behind bars, and andrew was dumbfounded.

andrew dixon: you know, my dad, no way, absolutely not. he was somebody that valued the human life. no way he would ever be involved in something of taking it away. so you're thinking, this is crazy. narrator: crazier still when he began learning the details. andrew dixon: i mean, it's all just wild. i mean, one of the smartest guys i know pays silver that can be tracked. you're thinking, that's absurd. narrator: dixon and shepard stayed silent for months. then shepard had a change of heart. interviewer: dave shepard starts to fill in the blanks-- he does. --about what happened next. yes, he does. is that true? [indistinct] narrator: he started talking and wouldn't stop. [indistinct] i promise i'll be compliant and won't cause any problems. [indistinct] narrator: coming up-- woman: he wanted me to call the ex-girlfriend and lie to her, say that i was having sex with her boyfriend, as well, for money. narrator: --how a plot to get revenge turned deadly--

narrator: --when "dateline" continues. [music playing] [coughing] copd isn't pretty. i'm out of breath and often out of the picture. but this is my story. and with once-daily trelegy, it can still be beautiful. because with 3 medicines in 1 inhaler, trelegy keeps my airways open for a full 24 hours and prevents future flare-ups. trelegy also improves lung function, so i can breathe more freely all day and night. trelegy won't replace a rescue inhaler for sudden breathing problems. tell your doctor if you have a heart condition or high blood pressure before taking it. do not take trelegy more than prescribed. trelegy may increase your risk of thrush, pneumonia, and osteoporosis. call your doctor if worsened breathing, chest pain, mouth or tongue swelling, problems urinating, vision changes, or eye pain occur.

♪what a wonderful world♪ [woman soft laughing] ask your doctor about once-daily trelegy for copd because breathing should be beautiful, all day and night.

[ screeching ] [ chuckling ] about once-daily trelegy for copd [ vocalizing ] that's a choice. [ vocalizing ] think of what we could do together. man: how are you? [indistinct conversation] narrator: three months after joe sonnier's murder, big dave shepard was in a police interview room, ready to tell all. he cut a deal with then district attorney matt powell. what the deal was, was basically, him tell the truth.

if we felt that he told the truth, then we would let him plead guilty to life without parole and waive the death penalty. where were you during his confession? i was in a different room, watching it. narrator: watching as shepard told detectives how his bromance with mike dixon started. narrator: and how they began spending more time together while they both went through their divorces. narrator: dixon talked about the women in his life, like richelle shetina. shepard even met her. narrator: dixon was crazy about her, but it didn't last. when shepard told detectives, when richelle took up with another man, another doctor named joe sonnier,

dixon didn't like it one bit. the two buddies tossed around some bizarre schemes to try and break up richelle and joe. zach johnson: david tells dr. dixon, if you really want to get to sonnier, you know what you need to do? you need to order him some gay porn magazine, and you've got to send it to his office. so did they do it or not? no, they don't do that. dr. dixon is like, nah, man, that's-- that's not-- i don't want to do that. it was a very-- narrator: another scheme they concocted to embarrass dr. sonnier involved hiring a woman shepard knew from a gentleman's club, named sheena teague. detectives spoke to her. so did we. he has a proposal for you. he said that his friend, dr. dixon, had been dating a woman and that she was now dating a doctor in lubbock. and he wanted me to call the ex-girlfriend and lie to her, say that i was having sex with her boyfriend, as well, for money did you say, why are you-- why do you want to do this?

no, i more laughed it off and told him that i would think about it. when you said you'd think about it, did he just drop it right away? yeah, we just-- just kind of left it there. he never asked me again. i think he got the gist that i wasn't going to do it. narrator: that idea sounded similar to that letter richelle received from someone named tina. remember, she alleged joe paid her for sex. police hadn't found her, since she gave no last name. now they thought the letter might have come from dixon and shepard. narrator: and shepard had more. narrator: he said dixon sent him to lubbock repeatedly to spy on richelle and joe. matt powell: there's no doubt in my mind they were stalking these guys months and months

before the murder took place. narrator: and detectives wanted to know how dixon's obsession turned from merely creepy to downright diabolical. this is go time. we're not turning back. and dave's like, oh my god, he wants this man dead. [indistinct] narrator: shepard said he then realized he would be the hit man for his friend dixon. and he described step by step how he did it. shepard said he got to lubbock around 4:00 in the afternoon. he sneaked into joe sonnier's backyard and waited for the doctor to come home.

narrator: 3.5 hours went by, nothing. and then shepard said he heard a rapping on the window. joe sonnier was inside his house looking right at him.

narrator: but that wasn't enough for him. narrator: after the murder, shephard drove the two hours back to amarillo. 24 hours later, he drove to a lake. it was around midnight. you feel like, despite everything he had done, he seemed quite credible? if you look at what he was saying,

match that up with everything else that we knew, it went hand in hand. so there wasn't very much doubt in our mind that he was telling the truth. narrator: and the next day, shepard led investigators to the gun. i remember driving up, seeing a drainage ditch. you brought david shepard back here? yes. he says, i'll show you where it is. gentlemen, i'll give you my best estimate, my best recollection, ok? narrator: he walked down one side of the lake and then stopped. he used a rock to demonstrate. i threw it underhanded, just like that, at an angle. it was in this quadrant. that's probably the closest i'm ever going to get [indistinct]. and he tosses that rock down there. and we've got the dive team guys over here looking, and we've got eyes on it. and sure enough, they go down. so they follow the path of the rock? they follow the path of the rock, and a couple of feet from the rock, boom, there's our murder weapon. narrator: so now the da had a confession and a murder weapon. and over the next year, lawyers on both sides

negotiated the terms of the deal. in exchange for shepard's statement, the death penalty was off the table. and in august 2013, he pleaded no contest to one count of capital murder. basically, he's confessing that he had been paid to kill dr. sonnier. narrator: but dr. mike dixon wasn't interested in a deal. he was determined to fight. he insisted to his attorneys that he had nothing to do with the murder. from day one, he made it very clear that he did not pay, he did not plan, and he did not participate in the killing of joseph sonnier. narrator: so dixon would roll the dice and risk a murder trial. and what happened in court would be unbelievable. coming up-- interviewer: he's on the stand. all is well. well, it wasn't all well very quickly. if there was probably ever a time in lubbock county to have a camera in the courtroom, that might have been it. narrator: disorder in the court.

interviewer: you really had to think on your feet. yeah, it was something. in 20-something years of doing this job, i had never-- i have never been part of something quite like that before. narrator: when "dateline" continues. [music playing]

mixer for only $56. dealdash.com, online auctions since 2009. this playstation 5 sold for only 50 cents. this ipad pro sold for less than $34. go to dealdash.com and see how much you can save.

hi. i'm richard liu with the hour's ton stories. donald trump announcing his nominations for key cabinet positions friday including billionaire scott bessent for treasury secretary, and republican congresswoman laurie chaves for labor secretary. former florida representative matt gaetz announcing friday he will not rejoin congress after when drew his name for consideration to be donald trump's attorney general amid sexual misconduct allegations. a special election to fill his seat will be april 21st, 2025. for now, back to "dateline." "

of a love triangle gone bad. for the woman in the middle of it all, richelle shetina, it was an unimaginable situation. she described it to a detective. aside from the thought of losing a child, this is the worst situation that i could ever imagine being in ever. interviewer: and i'm sure there's no closure. it's been awful. i don't even know who to trust anymore. i don't know who to talk to. and i-- narrator: when mike dixon's trial started in november 2014, richelle found herself at the center of the case. her former lover was accused of hiring a friend to murder the love of her life, joe sonnier. former da matt powell-- our theory it was an obsession with richelle shetina. this is vengeance. this is pride. this is jealousy. he spent months and months and months trying to destroy a relationship that she was in.

and so i don't know if it was just a vengeance deal for him or if some part in the back of his mind says, i may get her back. narrator: the state's star witness was mike dixon's former buddy, dave shepard. when you met with him before the trial, everything was on track. yeah, i mean-- interviewer: still on the same page. you had a deal. yeah, he was already done and received a life without parole sentence. narrator: dave shepard had one job to do for the prosecution. get up on the stand and repeat what he'd told detectives. narrator: da powell had shepard's taped confession. but now he needed the hit man to tell his story in person to the jury. interviewer: you're in the courtroom. he's on the stand. all is well. well, it wasn't all well very quickly. take us through how this all went off the rails. he started off taking the fifth. and he didn't have any right to take the fifth. then he'd changed his story. then he would mock me. he would pretend like he couldn't hear.

it was really just a sideshow. narrator: a sideshow with dave shepard as its ringleader. matt powell: if there was probably ever a time in lubbock county to have a camera in the courtroom, that might have been it. narrator: but cameras weren't allowed in the room when shepard told the jury his confession was a complete fabrication. he now said he'd acted alone and that dixon had nothing to do with the murder. are you thinking that i can't save this? well, what we tried to do was when he starts denying everything, we showed the videotape to the jury and see just the difference in demeanor between him on that videotape and the guy we were seeing in the courtroom. you really had to think on your feet. yeah, it was something. in 20-something years of doing this job, i have never-- i've never been part of something quite like that before. it hasn't been fun and hasn't been good and hasn't been entertaining.

narrator: and shepard stuck to his new story when his daughter visited him at the lubbock county jail after he testified. as far as dr. sonnier's death, nobody's involved in that but me. it was a terrible accident, my carelessness and stupidity, ok? nobody's responsible for that except me. you need to understand that. it was not intended. i wasn't paid to do that. why would you make the statement that mike paid you to do it if he didn't pay you to do it? because my attorneys, what they told me, when i did that statement to the police, my attorneys told me i needed to sell it. narrator: shepard's about face was pure gold for mike dixon's attorneys, dan hurley and frank sellers. interviewer: this is huge for your defense strategy. were you then surprised when he did that? that's what he consistently told me. no, mike did not pay. he didn't want anybody harmed. that was all me. mike didn't have anything to do with that. narrator: and the defense had its own star witness, dr. mike dixon.

dixon's attorneys hoped if the jurors heard from the man himself, they too, would be convinced he was innocent. so what does dr. dixon acknowledge was really in the works? dan hurley: he acknowledged that he was trying his hardest to get proof of joseph sonnier being with other women and not being committed to richelle shetina. narrator: on the stand, dixon stated he never asked shepard to kill dr. sonnier. what he did admit to was cooking up schemes to sabotage richelle's new relationship. he said he sent shepard to install cameras at sonnier's house, cameras he hoped would capture richelle's boyfriend with other women. he was going to use these photographs to show richelle that dr. sonnier was not who she believed that he was. narrator: the defense argued, when shepard arrived at sonnier's house, he went rogue and committed a brutal murder, which was never part of that plan. what is mike dixon guilty of?

where do we start? capital stupidity of the highest degree and trusting david shepard. what is mike dixon not guilty of? capital murder, murder. he never knew that this was going to happen. he never dreamed that it would be like this. narrator: after weeks of testimony, the jury was given the case. and they faced this dilemma about the state's key witness. interviewer: you had to make a choice-- believe story a, that was in the video confession with dave shepard, or believe story b, what the man was telling you, essentially, to your face in that courtroom. that's true. and that became a turning point for some of the jurors. narrator: jury foreman doug moore believed story a, shepard's taped confession, that mike dixon hired him to kill dr. sonnier. and moore expected everyone in the jury room would agree. he was wrong. because when the jurors took their first vote-- we had 10, guilty, and 2, not guilty.

narrator: but they kept talking. juror eric knight said there wasn't enough evidence to convict dixon. he found shepard to be bizarre. eric knight: there was something not right with him-- crazy, unstable. i'm not a doctor. i don't know for sure. but in my mind, i got the impression that something was not right. narrator: and he had a hard time believing this respected doctor was a criminal mastermind. eric knight: was it plausible that he did the murder for hire? of course. anybody, given a weak moment, could have done that. i just didn't see it as being that he wanted to kill somebody else. i didn't see him as being that vindictive. narrator: the jurors deliberated for hours and into the next day. but as they kept going-- doug moore: it began to become obvious that we had holdouts who were not going to change their mind. narrator: they were deadlocked. so they sent a note to the judge, and he declared a mistrial.

joe sonnier's sister missy was numb. i never thought about a mistrial. it was what? we've done all of this? we've sat here for all of these days for nothing. narrator: but for dixon's attorneys, this was a victory. dan hurley: it was, in my opinion, a huge battle to win, to get a hung jury. certainly wasn't the war, but it was-- as important. narrator: and they were charging ahead. dixon would face a second trial in 2015. interviewer: is mike dixon going to stop fighting? dan hurley: no, i don't believe he'll ever stop. [music playing] narrator: coming up, a new trial, a new jury. new problems for the prosecution? matt powell: every time you get a second chance, there's goods and bads about that. usually, retrials are not good for the prosecution. we get further away from the event.

you lose witnesses. narrator: when "dateline" continues. [music playing] finish ultimate, engineered for the toughest conditions. dry, burnt-on stains, old dishwashers, very hard water. finish ultimate with cyclesync technology helps deliver the ultimate clean. (♪♪)

let me set the record straight. helps deliver the ultimate are people born wicked? or do they have wickedness thrust upon them? oh! -ah! [ laughter ] no need to respond. that was rhetorical. hm, hmm. on october 26, 2015, it was deja vu at the lubbock county courthouse. after a hung jury, dr. mike dixon was back on trial. the once prominent plastic surgeon was accused of hiring dave shepard to murder joe sonnier. for sonnier's family, it was time to put on their game face.

i decided before the second trial that we should be confident as a family and support the da and really push this thing forward. how were you going to do things differently this time around? every time you get a second chance, there's goods and bads about that. usually, retrials are not good for the prosecution. we get further away from the event. you lose witnesses. but i think what we tried to do, we tried to streamline it better. narrator: the state didn't call dave shepard to testify a second time. instead, prosecutors played his taped confession. narrator: and this jury heard from paul reynolds, shepard's friend, and the man whose tip to police cracked the case wide open. maybe like 1:00 am. narrator: reynolds didn't testify in the first trial, but now in court, he backed up key details of what shepard said on the tape, including that his friend planned the murder with mike dixon. he was obviously obsessing about me.

narrator: and at this trial, richelle shetina was a key witness for the state once again. matt powell: i think she painted a picture of mike dixon. it was important for her to testify. there was no way we were not going to get away with putting her on the stand. he was just emotionally cruel. he would-- narrator: richelle painted a dark picture of dixon. she shared a similar one with detectives. richelle shetina: he'd pick out your weak point and then when he could, he would use it against you. he was just mean. he was a mean man, you know, and he presented himself kind of like underdog, as the mild-mannered, kind person. but he was just-- it was the worst relationship that i have ever had in my entire life. narrator: richelle said, when she moved on with dr. joe sonnier, she found her forever love. but dixon didn't seem willing to let her go. richelle shetina: he was obsessive when he was trying to get me back with him. narrator: the state also pointed

to something strange dixon did a few days after the murder. he tried to destroy messages on his cell phone. zach johnson: he erases the phone, resets it, and jumps into the swimming pool, just to make sure. interviewer: with the phone? zach johnson: with the phone, yes, with the phone. narrator: dixon eventually turned his phone over to the police, and a forensic expert was able to retrieve about half of his texts. what was in those messages, the state said, proved its case. there were a series of urgent texts between shepard and dixon in the middle of june. "got to happen tomorrow. i know. just need him to show. that's why you got to stick closer, to know his whereabouts. not trying to second guess, but we're getting down to the wire here." why is there a wire? why is there a time limit? why is there-- why is it important for him to show? why is it important for if he shows up, it's over? narrator: what they were doing, da powell argued, was planning a murder. but there was no evidence of murder either in the text messages. yeah, but are you going to put

evidence in a text message, saying, go kill the guy. obviously, you're not going to do that. instead of saying killing somebody, you'd say, "put it on him. we can't wait for him to get home. all i need is an opportunity. get it done." narrator: on july 10, 2012, the day of the murder, there were 37 texts and 4 calls between shepard and dixon. the day after, there were 21 texts, including one dixon fired off to shepard, once detectives left his house. "just had a visit from lubbock pd. ashe said you came by for cigars. they will see our texts and conversations. stay calm. lay low." yeah, i mean, it's hard to misconstrue that one. police were just there. and then all of a sudden, you're texting the murderer to lay low. narrator: but once it was the defense's turn, dixon's attorneys frank sellers and dan hurley argued not one of those messages pointed to a murder for hire. a lot was made of the text messages between david shepard and mike dixon. they don't look great at-- they look horrible. --face value.

something clearly was being planned. but you don't believe that it shows that murder was being planned? if you're walking down the street, and you found that phone on the ground, and you picked it up, and you looked at the text messages between mike dixon and david shepard, there is no way that you would think that these are texts about a murder, no way. narrator: but if dixon was innocent, why did he try to race the contents of his phone? interviewer: i think this is a problem people watching will have, is i wouldn't do that. if i had nothing to hide, i wouldn't start destroying all this evidence. they could say they wouldn't do it until they were in that same situation. everybody knows the feeling that when they get pulled over, even when it's just for speeding, and your heart drops, and your adrenaline starts to rush, imagine that on a much, much larger scale. and he's being wrapped up in a murder that he had nothing to do with, in the sense that he never wanted dr. sonnier dead. he did have a lot to do with david shepard,

but he was terrified, absolutely terrified. narrator: once again, the best person to make the defense's case was mike dixon himself. so for the second time, he took the stand. and he was adamant. dixon said he wanted dirt to make sonnier look bad in richelle's eyes, nothing more. dan hurley: he absolutely did not ever want david shepard to harm joseph sonnier physically. narrator: after four weeks of testimony, the defense closed with this. where was the proof mike dixon wanted joe sonnier dead? the defense said there was none. dixon's son andrew, was on edge. andrew dixon: we're just hopeful that this is it, and we're going to get him back, and he's going to kind of move past this. narrator: jury deliberations started. then just two hours later-- andrew dixon: we were just talking. and then when they came back and said, we have a verdict, and we thought he was kidding, that it was so fast.

narrator: coming up, the jury speaks again. all these things go through your mind. i was sobbing uncontrollably. narrator: but this case was far from over, when "dateline" continues. (♪♪) from celebration moments... ...to joyride moments. your moments are worth protecting against rsv. rsv is a highly contagious virus if you're 60 or older with certain chronic conditions, you're at higher risk of being hospitalized from rsv. and there are no prescription rsv treatments. you know how to protect against covid and flu. so ask your pharmacist or doctor about scheduling pfizer's rsv vaccine, too. because moments like these matter. go-friends, gather! keke! chris! jason! boop! friends.

let's go, let's go, friends! hold onto your dice. woohoo!! -nice frosting, pratt. -thank you! how we doin', keke? tastes like money to me. i can't go back to jail! wait, did you rob my bank? -hehe. -are we winning!? -ha ha ha! -oh boy! yeah! money, power, friendship. let's go! dad i got a huge barbeque wing stain. this bottle says i need to pretreat. that stuff has way more water. a little bit of tide goes a long way, so you can save your shirt and maybe even a little money. more money for nights at the... library. right... for a better clean with less... it's got to be tide.

♪ ♪ f ♪ something hasn changed within me ♪ ♪ it's time to try defying gravity ♪ ♪ ♪

november 18, 2015, judgment day for mike dixon, the former doctor waited for the jury's decision with his son andrew. andrew dixon: we got to actually sit back there with him and talk to him. it kind of, honestly, helped the nerves a little bit to see how he was and just at least be there with him. narrator: and andrew was by his dad's side for what came next. after deliberating for a scant two hours, the jury announced there was a verdict. and then you're thinking, is that good? is that bad? i mean, all these things go through your-- your mind. narrator: for andrew, it was bad, very bad. his dad was found guilty on two counts of capital murder. they kept saying guilty, guilty, guilty, yes, i found him guilty. and it was like a bad dream. narrator: but joe sonnier's family waited years to hear that one word. i was sobbing uncontrollably. i couldn't keep it together, because this was just a release.

and it felt so nice to know that we had gotten justice finally. i immediately just thought, it's over. we did it. it's over. we got him. reporter: anything to say, dr. dixon? narrator: dixon, the wealthy, talented surgeon, was sentenced to life in prison without the possibility of parole. but his attorneys promise this wasn't the end. dan hurley: we believe that this is round two of a deep and serious war. and we intend to do everything we can for the dixon family and for mike dixon. narrator: that included an appeal filed in 2016, a year after dixon's conviction. matt powell saw the filing as routine. matt powell: i remember getting their brief. and there was nothing there that we said, oh, gosh, i'm worried about that. the issues that were brought up were the same that we'd seen on hundreds of cases.

did you just kind of dismiss it, for the most part? i don't know if you dismiss it. but you don't worry about it. narrator: powell left the district attorney's office and went into private practice. and not long after, he got an unwelcome surprise. a texas appeals court overturned dixon's murder conviction. the former doctor would get a new trial. matt powell: the thought never crossed my mind that there would be a successful appeal on the case. narrator: dixon's appeal was won on two issues, how police collected certain cell phone evidence and restrictions on public access to the courtroom019, aftr three years in prison, dixon was released on $2 million bond. he was a free man. but his troubles were far from over. lubbock prosecutors filed their own appeal to a higher court. it was a hail mary. matt powell: it's extremely rare that the court of criminal appeals grants discretionary review of a criminal case, even a serious case like this.

narrator: but the higher court did take this one. and in january 2020, it ruled in favor of the prosecution. dixon's conviction was reinstated. and a few months later, in the midst of a pandemic, he was once again put behind bars. interviewer: is this where you take a deep breath? yeah, i took a sigh of relief. and there's some joy there. there's some relief. narrator: but only some relief. so this is remarkably still not over. yeah, still not over. there's other issues that the court said that the appellate team for the defense could address. narrator: but by 2022, a texas appeals court affirmed one of dixon's murder convictions, meaning he will continue to serve a sentence of life without the possibility of parole. as for the sonnier family, they take comfort in joe's legacy.

we spoke to them after that second trial. does he continue to guide you? in any decision in life, i like to ask or think, what would joe do in this situation? because he always took the right track. i think that i'm a better father because of the way my dad raised me. i know i'm a better husband. i'm a better friend. and i hope that he is proud of me. and i know that he is proud of me. when i think about him, i think about how he was-- he always pushed himself to be the best. but most of all, i just miss my big brother. [music playing]