This story has been updated.
Authorities have arrested a suspect in the "execution-style" shooting of a uniformed Texas sheriff's deputy.
Shannon J. Miles, 30, has been charged with capital murder in the fatal shooting of Harris County Sheriff's Deputy Darren H. Goforth, officials said Saturday afternoon.
Goforth, 47, was killed Friday night after exiting a Houston gas station convenience store.
Miles was charged with capital murder Saturday afternoon after being questioned as a person of interest by authorities. Police say they are not looking for additional suspects.
"We haven't been able to exact any details regarding a motive," Harris County Sheriff Ron Hickman told reporters, calling Goforth's death a "senseless and cowardly act."
"At this point, as far as we know, Deputy Goforth had no previous contact with the suspect," Hickman added.
Earlier Saturday, officials said a person of interest was taken in for questioning and was cooperating.
In an emotional news conference hours before Miles' arrest was announced, a visibly angry Hickman told reporters that "dangerous rhetoric" against law enforcement had "gotten out of control."
In an emotional news conference Saturday afternoon, a visibly angry Hickman told reporters that "dangerous rhetoric" against law enforcement had "gotten out of control."
"We've heard black lives matter — all lives matter," he said. "Well, cops' lives matter, too."
Miles has a previous criminal record, which includes trespassing and disorderly conduct with a firearm, Hickman said. A weapon from Goforth's shooting was recovered, and ballistics tests "indicate it is a match" with a weapon belonging to Miles, he added.
Goforth had just filled up his patrol car at a Chevron gas station around 9:30 p.m. ET when a man "walked up behind him and literally shot him to death," Hickman said at a news conference overnight.
After Goforth crumpled to the ground, the suspect towered over him and fired several more shots.
"It appears to be an unprovoked execution-style killing of a police officer," Hickman said.
Earlier, police had described the suspect as a male with a dark complexion who was in his 20s, wearing a white T-shirt and red shorts. He was reportedly driving a red or maroon Ford Ranger with an extended cab.
Investigators did not know what the motive was and believe the suspect targeted the married father of two simply because he was in uniform.
"The motive for this is absolute madness," Hickman said.
Harris County District Attorney Devon Anderson said Saturday that law enforcement needs support despite there being a "few bad apples" — an apparent reference to the recent spate of police shootings of unarmed people.
"There are a few bad apples in every profession. That does not mean there should be open warfare declared on law enforcement," she said. "The vast majority are here to do the right thing. They care about their community. What happened last night is an assault on the fabric of society."
Hickman added that it was "time to drop the qualifier" in the rally cry, "Black lives matter," which has proliferated online following the police shootings of Michael Brown and other young black men.
Houston Mayor Annise Parker ordered city flags lowered after Goforth's killing.
On Saturday morning, balloons, flowers and candles were placed at the Chevron station gas pump that Goforth used before he was killed. A note at the impromptu memorial read, "Gone but never forgotten R.I.P Deputy Goforth," The Associated Press reported.