A former Utah state trooper suspected in several Dallas-area roadway shootings that killed at least one motorist died on Christmas Eve, a hospital official said.

Brian Smith died at 6 p.m. Wednesday at Parkland Hospital in Dallas, said nursing supervisor Arthur Clarke.

The 37-year-old had been in critical condition on life support from a self-inflicted gunshot wound. Police say he shot himself in the head after a brief standoff early Tuesday, more than six hours after the roadway shooting spree ended.

Dallas police said they think Smith was responsible for at least one death that resulted from the shootings. They declined to comment on another death in neighboring Garland because it was outside their jurisdiction.

Dallas police Lt. Craig Miller said authorities were working to confirm their belief that Smith was the gunman in separate shooting deaths minutes apart Monday on a street in the suburb of Garland and a Dallas interstate.

Earlier Wednesday, police shut down the freeway to re-examine the scene of one of several of the shootings.

Miller and a Garland police official said both departments were waiting for ballistics tests to come back for possible matches of bullet casings.

"It's just another thing that's part of the investigation," Miller said of the second freeway examination. "It's not a critical component. That's what we wanted to do, just check everything we can."

Warrants for Smith's arrest had been issued in the Fort Worth suburb of Southlake, where authorities have obtained evidence linking him to two robberies in the past eight days.

Both incidents involved thefts in which purses were stolen from women in vehicles parked at businesses on Southlake Boulevard, the main artery connecting Southlake and Keller, where Smith lived.

Police have tied Smith to the incidents through witness identification and video of him using a credit card of one of the victims, Southlake police spokesman Mike Bedrich said.

One of the warrants seeks Smith's arrest on a charge of aggravated robbery for spraying an unknown substance in the victim's face, Bedrich said.

"Our portion of this is only a snippet of a larger unfortunate chain of events," he said.

Smith moved to Keller with his wife and children last spring, just months after his conduct came under scrutiny from the Utah Highway Patrol. His peace officer certification was revoked after he went on a drinking binge and threatened to kill himself.

The family moved to Keller in part because Smith's wife, Angela, has relatives in the area, according to Cindi Schut, a former neighbor in Utah.

In March, Tarrant County records show, Brian and Angela Smith obtained a $215,200 loan to buy their home, which has an appraised value of $276,100. The 3,300-square-foot home has five bedrooms and 3 1/2 baths.

Friends, coworkers and neighbors of the former Utah state trooper struggled to make sense of the case.

In Utah, where Smith's problems as a trooper are just now coming to light, he's remembered as a good father who never lost his temper and coached youth soccer and basketball.

"This is a shock for everyone who knows Brian," said Michael Peterson, Smith's former bishop in the Mormon church. "Obviously, he was struggling with some things. But the Brian Smith that everyone around here knows would never have done any of these things."

Schut, who lived across the street from the Smith family in the Salt Lake City suburb of Riverton, said she knew Brian Smith had problems, but had not delved into them out of respect for the family's privacy. A Christmas card received a few days ago from the family gave no hint that anything was amiss, she said.

"It just said 'Hi from your neighbors. We miss you and the kids playing and hope everybody's happy and doing well,"' she said. "I wonder if they were still here if he'd be doing OK."

A current neighbor in Keller, Karen Baughman, said Smith and others members of his family came to her door just last Sunday to offer Christmas cookies they'd brought from church — an act she described as typical.

"He was just hanging Christmas lights two weeks ago," she said. "I mean, this is dumbfounding."

Smith made it known that he had left law enforcement in Utah to take a job in sales with IBM in the Dallas area, Baughman said. But nobody would have suspected problems in his past, she said, because he was such a clean-cut person.

"When my husband offered him (a beer), he declined it, even though his family was still back in Utah," she said.

The IBM media relations office did not immediately return a call from The Associated Press seeking information on Smith's employment.

The Garland shooting Monday happened at a major intersection, when a driver pulled up alongside a small Nissan and shot and killed the Nissan's driver, 20-year-old Jorge "George" Lopez of Rowlett, said Garland police spokesman Joe Harn.

Three semitrailer drivers were later shot at on Interstate 635, and one of those three died. William Scott Miller, a 42-year-old married father of two from Frankfort, Ky., was on his way to get on a plane for a trip home to his family for the holidays.

Harn said Garland police are still waiting for tests to determine if the gun Smith used on himself is the same one used in Lopez's death.

"I can tell you this: There's nothing telling us so far that it's not him," Harn said.

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