"I looked over at Ryan and he was holding it," Román added.
Román said Greathouse placed the weapon against Fox's chest and fired twice."
"It all happened really fast," Román said. "I heard two shots and between those two shots the scream of a woman."
Román said Greathouse began crying and told him that he had shot his sister. Román said he drove Greathouse to his home after agreeing to take the blame for the shooting and intending to flee to Mexico.
Román who later confessed to police that he, Román, had shot the deputy said Thursday that Greathouse had threatened his family.
"He said, 'Remember you have two children in high school and if you say anything the same thing will happen to them,' " Román recalled.
When defense attorneys asked Román why he didn't mention this following Ryan Greathouse's death from a drug overdose in April 2010, which ended the potential threat, Román answered that this was his first chance to testify.
Police have testified seeing Greathouse's Ford truck and Román's Cadillac leave in separate directions following the meeting on McCornick Road, where the drug deal allegedly occurred.
But Román explained that a third man who was with them someone whose name he does not remember had agreed to drive Greathouse's truck home while Román and Greathouse went to collect the money.
Fox's sergeant, Rhett Kimball, has testified he saw two vehicles stop briefly on a rural road near McCornick. He ordered Fox to follow the Cadillac and gave her the go-ahead to make the traffic stop just outside of Delta because there was a question about whether the owner of the car had an outstanding warrant.
"10-4," Fox said over the radio just after 1 a.m. on Jan. 5. "I'll be over by the ballpark."
Those were the last words anyone heard from the 37-year-old deputy, prosecutors say, other than Román.
Román, 40, is charged in 4th District Court with first-degree felony aggravated murder and felony counts of evidence tampering and illegal possession of a dangerous weapon.
According to testimony earlier this week, Román fled north to Nephi and later to Salt Lake City, following the shooting. From there, he and another man, Ruben Chavez-Reyes, rode buses and TRAX trains south. They took a limousine around Utah County and later a cab to Beaver for $300. There they hoped to find a friend who could help them flee to Mexico, police said.
The men, unable to find their friend, hid out in a shed, burning burlap and gasoline to stay warm. In the morning, they were awakened by police and arrested.
Prosecutors had intended to seek the death penalty, but Judge Donald Eyre ruled last month that Román's IQ was below 70. By legal definition that means Román is mentally retarded and prosecutors cannot seek the death penalty.
If convicted of murder, Román faces possible sentences of 20 years to life or life without parole.