The man charged with Tuesday's fatal shooting of a Utah sheriff's deputy had just sold drugs to a brother of the slain officer on a remote desert road, according to court papers and a family member.

Roberto Miramontes Roman was charged about 10 hours after the shooting with capital murder and tampering with evidence. A manhunt led authorities to a west Salt Lake City neighborhood, where police believe they saw him run from a house and disappear.

Roman, 37, is accused of leaving Deputy Josie Greathouse Fox dead from a gunshot wound after a traffic stop near Delta, about 130 miles southwest of Salt Lake City. If caught and convicted on the murder charge, Roman could face the death penalty.

Roman had just sold drugs to Ryan Greathouse, according to court papers. Ryan Greathouse is the deputy's brother, their mother told The Associated Press late Tuesday.

"He's pretty upset," Cindy Greathouse said. "We have a lot of good friends and neighbors who have been here today and lots of support."

Ryan Greathouse was not immediately available for comment, she said, declining to comment further.

"Even in a town this small, it's a huge coincidence. It's a bizarre irony," Millard County Deputy Attorney Patrick Finlinson said late Tuesday of the brother-sister connection.

Less than an hour before the shooting, another deputy saw two cars meet on a dirt road. One of the cars was traced back to Ryan Greathouse, who told deputies he bought drugs from Roman and another man during the encounter.

Greathouse also provided police with Roman's cell phone number and identified him from a photograph, court papers say. Detectives later traced a signal from Roman's cell phone to a tower along Interstate 15 in Salt Lake County.

Police converged on a home in Salt Lake City where Roman is believed to have relatives, but nobody was found inside the house, a shed or a trailer after an hourslong standoff.

City police seized an orange Corvette at the residence. Court papers say the car's license plates were bolted earlier Tuesday to a gray Cadillac seen by Millard County Sgt. Rhett Kimball during the alleged desert drug transaction.

Kimball had radioed Greathouse Fox to stop the Cadillac as it headed toward Delta on state Route 50 about 1 a.m. Tuesday. Nine minutes later, Kimball found Greathouse Fox dead on the highway, court papers say.

Greathouse Fox, a five-year veteran of the department, leaves behind a husband and two children.

A warrant was issued for Roman's arrest Tuesday morning. Fourth District Court Judge Donald Eyre set bail at $50 million cash.

Authorities also are looking for Ruben Chavez, the owner of the Cadillac, who has not been charged.

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