joseph sonnier?pard was doing was really only to get pictures of dr. sonnier out with other women so that he could show them to richelle and say, "this guy is cheating on you." >> shepard's reporting back, "oh, i couldn't find him. and i think mike became frustrated with it and it's evident from the messages that he was sending. >> so then "go get him" and "whip and spur"? go get who? >> use of lots of texas panhandle colloquialisms, like, "get her done, put it on him, go get him." he had a history of using that language with lots of different people. >> and the reason they say mike dixon was so upset was they felt richelle shetina was trying to throw the relationship with joseph sonnier in mike dixon's face. >> in court, the defense pointed to texts between shetina and dixon when she backed out of that planned vacation. she texts. i'm in love. enjoy your get away. when dixon asked who's the lucky guy? she replies new dance partner. >> and so mike was just -- his ego was deeply bruised. and he wanted

joseph sonnier as a witness. >> i knew they had the right guys. in my mind there was no other possibility. >> reporter: shepard pled gill doit murdgillty to the murder. enturder trl, a bombshell, shepard did a 180, saying his friend didn't put him up to the murder. >> theis is the kind of moment you typically see in a movie. that stuff doesn't typically happen in real courtrooms. >> reporter: after the about face on the witness stand, the jury was hung and dr. dickson released. >> i was devastated. i couldn't breathe. i couldn't think. >> reporter: do you think he was the biggest factor to getting that hung jury? >> absolutely, 100%. >> reporter: prosecutors didn't give up. in 2015 a second trial. >> amarillo doctor michael dickson is back on trial for capital murder. >> reporter: this time dr. dickson was convicted with the help of shepard's own daughter haley who testified that their meyl askedhi hou r sdene rk for y d hwo'tell us about it. don't worry about it. >> the verdict is in. >> unanimous verdict. >> guilty of two charges. >> he said gui