Idaho State Police
Police in Utah and Idaho believe the driver of this Jetta shot and killed another driver on I-84 in Box Elder County on Wednesday night, before leading Idaho authorities on a chase and crashing into a canal. The alleged gunman, Jonathan Llana, 45, ran off after crashing.

SALT LAKE CITY — A manhunt continued Thursday in Idaho for a man who authorities say shot and killed a motorist in Utah without warning and for no apparent reason.

"There is nothing that (the passenger) has told us that leads us to believe there was any interaction prior to the shooting," said Utah State Bureau of Investigation Lt. Ryan VanFleet.

"Nothing that we've been able to uncover so far indicates a road rage incident or any previous interaction."

Dennis Gwyther, 50, of Salt Lake City, and another man were driving on I-84 from Utah to Boise, when the shooting happened about 8 p.m. Wednesday. VanFleet said both men work in the airline industry and were headed to Boise for work. According to his Facebook page, Gwyther worked for SkyWest Airlines as a flight attendant.

By Thursday afternoon, the Box Elder County Attorney's Office formally charged Jonathan Mendoza Llana, 45, of Los Angeles, with aggravated murder and attempted aggravated murder, both first-degree felonies. The charges come as authorities continued to search for Llana in Idaho.

Wednesday night, near Snowville, Box Elder County, in the Rattlesnake Pass area, a semitrailer was attempting to a pass another semitrailer, briefly causing a slowdown of traffic as the semis were side-by-side on the two-lane road, VanFleet said.

Just as Gwyther, who was driving a Range Rover, got past the semitrailers and traffic began to open up, a silver Volkswagen Jetta pulled up next to them and the driver shot at the Range Rover, VanFleet said.

Llana fired multiple shots into the vehicle, according to charging documents.

Gwyther was killed and his passenger was injured. An off-duty paramedic who was also on I-84 stopped to help, but VanFleet said there was nothing he could do.

Gwyther's vehicle went off the side of the road before coming to a stop. The passenger, whose name was not released, called 911. He was taken to Bear River Valley Hospital with injuries not considered to be life-threatening.

Officers put out an "attempt to locate" alert to other agencies in Utah, Idaho and Nevada, telling them to be on the lookout for a silver Jetta with a "unique antennae" and an out-of-state license plate.

"Shortly after, Idaho State Police attempted to stop a silver Jetta that fit the suspect description. The vehicle fled from ISP and eventually crashed in a canal," UHP stated.

VanFleet said Idaho authorities initially pulled the vehicle over before it sped away. It crashed in Cassia County near Burley, Idaho, where I-84 and I-86 meet.

The driver of the Jetta ran off after crashing in the canal before police could catch him.

Based on who the Jetta is registered to and a description of the driver, Idaho authorities announced they were looking for Llana. They warned that he should be considered "armed and dangerous."

VanFleet noted that a weapon was found in the wrecked car, but he did not know if it was the same one used to shoot and kill Gwyther.

The Department of Public Safety helicopter was sent to area to assist in the search. VanFleet said authorities believed they had the area contained where they thought Llana may be.

"I think everyone is confident that we know the area where he is," he said.

He described the area as mostly open fields with some residential homes, which authorities from the Idaho State Patrol and Cassia County Sheriff's Office were searching, VanFleet said.

Llana does not have an extensive criminal history, he said.

Gwyther is survived by Matt Gwyther. The two were married the day gay marriage became legal in Utah, according to a statement from Matt Gwyther.

"He loved his family. His family was the most important thing in his life," according to the statement from the Gwyther family. "He enjoyed being the bonus dad to his two teenage kids. Loved to have fun and laugh. A kid inside an adult body. Always kidding around and playing jokes."

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His family said Gwyther enjoyed "gadgets" and "could create anything, especially if it involves wiring. He did sound and lighting for many clubs in Salt Lake. He was an entrepreneur and always looked for new opportunities.

"He was a strong advocate for LGBTQ rights and used his connections to help wherever he could. His life was tragically taken while commuting to his job as a flight attendant based out of Boise. We are still in shock and have not processed much as the suspect is still at large and investigation is pending. We want him caught and swift justice," the statement concluded.