HARRIS COUNTY – Shannon J. Miles has been charged with capital murder in the death of Harris County Sheriff's deputy Darren Goforth, according to the Harris County Sheriff's Office.

Miles, 30, was located after authorities performed routine research in searching for the vehicle spotted at the crime scene, Sheriff Ron Hickman said in a press conference Saturday afternoon.

Hickman said Goforth was brutally gunned down by Miles while at a northwest Harris County gas station Friday evening. So far there is no motive and no known connection between Goforth and Miles.

Miles apparently has a lengthy criminal history including six previous arrests; two for using force against an officer, including a Harris County deputy.

Miles also used to play football for Cypress Falls High School in the Cy-Fair district.

Miles refused to talk to KHOU 11 News Saturday evening but is claiming he is innocent.

Hickman said there were multiple witnesses in the incident, and he is asking them -- as well as anyone else with information -- to come forward.

Friday evening Goforth was walking out of a Chevron gas station at the corner of Telge and West Road when Miles apparently approached him and shot him multiple times in the back. Goforth had stopped at the gas station to fill up his patrol car, the sheriff's office said.

Goforth, 47, was a 10-year veteran with the sheriff's office, working the west district patrol division. He leaves behind a wife and two children.

"It appears to be an unprovoked, execution-style killing of a police officer," Hickman said. "It strikes us all at the heart of public service."

Hickman said in his 45 years of law enforcement, he can't recall another incident "this cold blooded and cowardly."

Goforth had finished investigating a traffic accident about 30 minutes before he was killed, according to Hickman.

It doesn't appear there was any connection between the traffic investigation and the shooting.

Goforth was working alone Friday evening, which is common procedure, spokesman Thomas Gilliland said.

"This is an act of cowardice and brutality, the likes of which I've never seen," said Harris County District Attorney Devon Anderson. "We will use all our resources to prosecute him to the fullest extent of the law."

Goforth's wife, Kathleen released the following statement Saturday evening:

"There are no words for this. All the language that I know is inadequate for what I want to express. But for Darren, I will try. I can't describe him with cliches and platitudes. My husband was an incredibly intricate blend of toughness and gentility. He was loyal...fiercely so. And he was ethical; the right thing to do is what guided his internal compass. I admired this quality, perhaps, the most. For that was what made Darren good. And he was good. So, if people want to know the kind of man he was...This is it. He was who you wanted for a friend, a colleague, and a neighbor. However, it was I who was blessed so richly that I had the privilege of calling him my husband and my best friend. - Kathleen Goforth"

The 100 Club, a Houston-based nonprofit organization supporting dependents of law enforcement officers and firefighters killed in the line of duty, announced Saturday it will provide a $20,000 check to Kathleen, their 12-year-old daughter and 5-year-old son to help with immediate financial needs.

Photos: Suspect ambushes deputy in NW Harris County

Meanwhile, as news of the deputy's murder spread throughout the city a shrine began to grow around the gas pump where he died. Visitors left flowers, balloons and handmade tributes in Goforth's memory.

"I've talked to him several times about his family," said Brian McCullar, who lives in one of the subdivisions near the crime scene. "I know that they just recently got back from a vacation. I know he couldn't wait to go on vacation with his family."

Hundreds gathered Saturday evening to grieve and pray for the officer and his family.

Several of the people who came to the pay their respects were especially disturbed by the sudden and mysterious circumstances surrounding the deputy's death.

"I mean, he was doing his job, but he was just standing there," said Barbara Adams, who lives nearby. "The cold-bloodedness of it really hit me."

A couple of past and present law enforcement officers echoed that concern, pointing out that the murder had no apparent motive.

"You go on duty and you expect the unexpected," said McCullar, a former deputy constable. "But when you're going off duty and you're filling up your patrol car? I don't think that you're expecting that."

A woman who declined to offer her name but volunteered that she's a police officer visiting Houston from Virginia spent several minutes making and posting hand-drawn cards.

She said she saw patrol cars in the area and heard about the deputy's death from her colleagues back in the Washington DC area.

"It's just heartbreaking, you know?" she said. "It's a hard job and we're here to help serve and protect. And through no fault of his own, he was pumping gas and somebody decided to end his life because of the hate in their heart."

The seemingly random killing had some residents of the area questioning whether their neighborhood is becoming too dangerous for them.

"If a deputy sheriff can be executed and murdered in the same area that I live in, I mean what's the hope for older people and defenseless people," said Hugh Benziger, who lives near the crime scene. "That could've been some old lady, an elderly person buying gas."

Texas Attorney General Ken Paxton released the following statement Saturday evening regarding the death of Deputy Goforth:

"Acts of violence against our brave law enforcement in Texas will not be tolerated. We should take all steps necessary to prosecute those who commit them to the fullest extent possible under the law. I commend the Harris County Sheriff's office and the Harris County DA's office for their swift work apprehending and charging this dangerous criminal for this heinous murder of a Texas law enforcement officer. The Texas Attorney General's office extends its deepest condolences to Deputy Goforth's wife and children, family and friends during this time of unimaginable grief. We should never forget the sacrifice that law enforcement and their supportive families make when officers go out each day to ensure the safety of our families and the safety of our communities."