Sheppard told the court it was Anthony James Prater who pulled the trigger in the early morning hours of Nov. 27, 2007, that it was Prater's gun, Prater's idea, Prater's revenge.
"I didn't know anything, I didn't know if anybody had been hit at the time, all I knew was [Prater] shot out of my car," Sheppard said. "He kept laughing, like it was funny."
But defense attorneys said Sheppard, who they claim was the triggerman, presented the story he thought would get him the best plea deal not the truth.
"As you sit there, you, Ryan Hal 'Scarface' Sheppard are charged with murder," said defense attorney Edward Brass. "But what you're telling us is your truth, your version, because you knew [the police] were going to treat you differently if you admitted you were the driver."
Sheppard, who is scheduled for a review hearing next month, said he hasn't been promised anything in exchange for his testimony. He stuck to his story: that he had been an unwitting participant to the murder.
"You can't change the fact that it was my car and I was driving," Sheppard said. "The truth's the truth."
He was high on methamphetamine at the time, he said, and didn't want a gun in his car. He told Prater to get rid of it. He thought that Prater had, until the shooting happened.
"You must have said it 60 times that you're telling the truth today," Brass said during his cross-examination of Sheppard. "And in the middle of all this truth-telling, all this cleansing, you've lied."
Prater, 28, was charged in Samora's murder with aggravated murder and obstruction of justice, both first-degree felonies, and five counts of discharging a firearm from a vehicle, a third-degree felony. If convicted, he faces the possibility of life without parole or 20 years to life in prison.
Prosecutors have said Prater was motivated to kill Samora because two years prior, Samora testified in court against Christopher M. Archuleta, Prater's former cellmate.
Sheppard, 31, is charged with first-degree counts of murder and obstruction of justice, as well as third-degree felony discharge of a weapon from a vehicle. He has spent time in and out of jail and drug rehabilitation centers.
Prosecutors also called to the stand Ali Al-Rekabi, who has known Prater for about two decades and exchanged letters with him in jail.
Al-Rekabi, who is serving time for aggravated assault, walked into the courtroom escorted by two armed guards. He wore an orange jump suit, and sat with his hands shackled and legs bound.
He spoke about the letters, which he said Prater had asked him to write, outlining a motive for Sheppard to kill Samora.
Al-Rekabi wrote that Sheppard had sought his advice while they were both living at the Northern Utah Community Correctional Center in Ogden. Sheppard, he wrote, was having trouble with a woman and needed a gun "big enough to get rid" of her ex-husband, Samora.
"So this letter you wrote, the whole thing was a lie?" asked prosecutor Vincent Meister.
"Yes," Al-Rekabi said. "All of it."
Al-Rekabi said he thought the letter was sent to Prater's defense counsel. But defense attorneys denied receiving a letter from Al-Rekabi, and said the conversations he told the court he had with Prater never happened.
Al-Rekabi also told the court Prater had gloated about the shooting.
"He said he got [Samora]," Al-Rekabi testified. "He said nobody knew but [Sheppard.]"
Prater's trial, before Judge Robin Reese, is scheduled to last through the week.