Woman at the Center of Texas Doctors Love Triangle Murder-for-Hire Case Speaks for First Time

Richelle Shetina speaking out for the first time in a "20/20" exclusive.

“Evil followed me straight to Joseph's door,” Shetina told ABC News’ “20/20” in an exclusive interview. “This good and kind and decent and loving man. Like it or not evil followed me right there.”

Authorities made the connection when they received a tip from a man who said his friend named David Shepard told him he killed a man in Lubbock. Police learned that Shepard was friends with Dixon.

Investigators also discovered surveillance videos of Dixon and Shepard together the day after the murder. David Shepard accepted a plea deal in 2013 for Sonnier’s murder and is currently serving a life sentence.

Dixon was charged with first-degree murder and while on trial, prosecutors argued that Dixon hired Shepard to kill Sonnier because he was obsessed with Shetina and jealous that she was dating another man. They claimed Dixon had paid Shepard in silver bars to spy on the doctor at his Lubbock home and then kill him. But Shepard – who first admitted to authorities that he was in cahoots with Dixon when he committed the murder – changed his story at trial and claimed he had acted on his own.

The defense argued that Dixon never wanted Sonnier dead, and that Shepard was paid three silver bars as a business investment for a company they were starting. The trial ended in a hung jury.

Dixon went to trial a second time this past fall and was found guilty of two courts of capital murder charges in November 2015. He was sentenced to life in prison without the possibility for parole.

As for Shetina, the woman prosecutors claim was Dixon’s obsession, she is now trying to move forward with her life.

“There are real sociopaths and psychopaths that walk amongst us… They're charming, and they are witty. And they sit at the dinner table with you and your children. And sometimes they sleep in your bed with you,” Shetina told “20/20.” “They're not capable of feeling love for you or empathy for anyone… When the mask starts to slip-- when you see that, don't ignore it. Don't try to rationalize it… And get out as fast as you can. Truly. Run as fast as you can.”