Al Hartmann,
Roberto Roman enters 4th District Court in Spanish Fork Monday Aug. 13, 2012. He is on trial for the killing of Millard County sheriff's deputy Josie Greathouse Fox.

SPANISH FORK — In an unexpected twist, a man on trial for allegedly shooting and killing a Millard County sheriff's deputy testified Thursday that the woman's brother was responsible for her death.

Roberto Miramontes Roman, 40, is charged with murdering deputy Josie Greathouse Fox during a traffic stop near Delta on Jan. 5, 2010. On the fourth day of his trial, Roman took the stand and testified that the shooter was actually Fox's brother, Ryan Greathouse.

"He basically said it was Ryan Greathouse that did the shooting," defense attorney Steve McCaughey said, "and that Ryan Greathouse threatened him and threatened to kill his kids and that's why he covered for him."

Roman was on the stand for close to 90 minutes and prosecutors are expected to continue cross examining him Friday.

Roman testified that Ryan Greathouse was in the car with Roman when the car was stopped and he took the gun, said Millard County Chronicle Progress reporter Dean Draper. Ryan Greathouse allegedly leaned across Roman's chest and fired before realizing the police officer was his sister.

Ryan Greathouse was found dead in a Las Vegas bedroom a few months after the shooting.

According to evidence from a previous court hearing, Roman was taking a drive and smoking methamphetamine with Ryan Greathouse earlier that evening. Roman allegedly told police that he was angry when Fox pulled him over because he had taken care to stay in his lane and follow the speed limit. Believing he was being stopped "because he was Mexican," Roman reportedly told police he caught a glimpse of the deputy and immediately started shooting, according to court testimony.

Fox, 37, died after being shot in the chest.

That explanation of events was reiterated by prosecutors in opening arguments at trial.

Roman was originally facing the possibility of the death penalty, but 4th District Judge Donald Eyre determined that Roman is "mentally retarded" and ineligible to receive a death sentence.

In addition to aggravated murder, a first-degree felony, Roman is charged with tampering with evidence and possession of a dangerous weapon by a restricted person, third-degree felonies.

Though the trial is scheduled through Aug. 24, the case could go to the jury on Friday.