The jury took seven hours to deliberate, finding Prater guilty of first-degree counts of murder and obstruction of justice, as well as five counts of third-degree felony discharge of a weapon from a vehicle. He will be sentenced May 6.
Typically, a guilty verdict on these charges would mean prison for life without parole or for 20 years to life.
According to prosecutors, Prater shot 35-year-old Samora in a drive-by on Nov. 27, 2007.
In closing arguments Thursday, prosecutors said the shooting was an act of revenge meant to silence the man who testified against Prater's "homeboy" in a 2005 shooting case. They called Prater unapologetic and calculated, and said that after he killed Samora, he tried to get rid of evidence and intimidate potential witnesses with threats and violence.
"After he shoots Vincent Samora eight times, what does Anthony Prater say? Oops? Uh-oh? No. He says, 'I know I got him,' " said Deputy Salt Lake County District Attorney Vincent Meister. "He told all these witnesses, 'You're dead if you testify.' That fear is very real; it hasn't gone away."
But defense attorneys insisted Prater was framed.
"The reason you should find Mr. Prater not guilty is very simple: Ryan Sheppard shot and killed Victor Samora," said defense attorney Edward Brass. "Where's the physical evidence tying this shooting to Mr. Prater? Where is it? There isn't any."
Sheppard, 31, admitted to driving the car out of which Prater shot Samora. He's been charged with first-degree counts of murder and obstruction of justice, as well as third-degree felony discharge of a weapon from a vehicle. But he agreed to testify in this case in order to secure a plea deal.
Defense attorneys pointed to the plea agreement as a motive for Sheppard to lie.
"[Sheppard] is told, the first person who comes in and tells us what we need to hear is going to get the best deal," Brass said. "So, what does he do? He comes in and says, 'Yeah, my car was there. But I was the driver. I didn't shoot anybody,' and he gets himself a deal."
Prosecutors said deal or no, Sheppard's testimony should demonstrate just the opposite.
"When the defense talks about the wonderful deal these witnesses got, they fail to mention that these witnesses get to live with the label of 'snitch' for the rest of their lives," Meister said. "Their risk dramatically increased the second they walked into this courtroom."
Prosecutors closed by saying the jury must rule based on evidence, and the defense had not outlined enough evidence against Sheppard to exonerate Prater.
Prater, who wore a deep blue suit and glasses, remained expressionless as both sides made their closing remarks.