HOUSTON (AP) — A man charged with killing a suburban Houston officer first shot the 10-year veteran in the back of the head and fired a total of 15 times, authorities said Monday.

Shannon J. Miles, who is accused of capital murder and whose criminal record includes convictions for resisting arrest and disorderly conduct with a firearm, appeared briefly in state District Court in handcuffs and shackles. The 30-year-old Houston resident said little, other than to answer the judge's questions. He's being held without bond.

Harris County District Attorney Devon Anderson would not comment on a motive, saying investigators were still trying to figure that out. When asked if it might be connected to heightened tensions around the country between law enforcement and civilians, Anderson said, "I have no idea whether it does or not."

This weekend, Sheriff Ron Hickman said the attack was "clearly unprovoked," and there is no evidence Goforth knew Miles. "Our assumption is that he (Goforth) was a target because he wore a uniform," the sheriff said.

Anthony Osso, one of Miles' two court-appointed attorneys, told The Associated Press that his client intends to plead not guilty.

"He had indicated to the investigating officers that he was not involved in the case," Osso said in a telephone interview after Monday's hearing.

Osso said Miles' defense team is distancing itself from the sentiments expressed by the sheriff, the district attorney and others.

"What I want to do is investigate the case and defend my client based on the facts of the case and not opinion in the public eye or rhetoric that's espoused on social media. It's difficult enough to handle these types of cases," Osso said.

In court, Anderson read the probable cause statement, saying that police first received a call at 8:20 p.m. Friday. When authorities arrived at the gas station in the Houston suburb of Cypress, they found Deputy Darren Goforth, face-down. He was already dead, she said.

Surveillance video from the gas station showed Goforth, 47, had just come out of a convenience store after he had pumped gas and that Miles got out of his red truck, she said.

"He runs up behind Deputy Goforth and puts the gun to the back of his head and shoots. Deputy Goforth hits the ground and then he continues to unload his gun, shooting repeatedly into the back of Deputy Goforth," Anderson said.

Goforth was shot 15 times and a witness saw the shooting, Anderson said. She added that the shell casings match the .40-caliber Smith and Wesson handgun found at Miles' home.

Miles' next court date is Oct. 5.

The killing evoked strong emotions in the area's law enforcement community, with Hickman linking it to heightened tension over the treatment of African-Americans by police. Goforth was white and Miles is black.

The nationwide "Black Lives Matter" movement has sought sweeping reforms of policing. Related protests erupted in Texas recently after Sandra Bland, a black woman, was found dead in a county jail about 50 miles northwest of Houston three days after she was arrested on a traffic violation.

"We've heard Black Lives Matter, All Lives Matter. Well, cops' lives matter, too," Hickman said Saturday.

Houston Police Lt. Roland De Los Santos, a childhood friend of Goforth's, called the deputy a "simple guy" who was focused on providing for his family, noting that Goforth's wife is a teacher and the couple has a 12-year-old daughter and a 5-year-old son. Goforth's funeral is planned for Friday, he said.

Miles' criminal record stretches from 2005 to 2009, with three convictions for resisting or evading arrest, as well as convictions for disorderly conduct with a firearm, criminal mischief and giving false information to police. Records show he was sentenced to several short stints in jail, anywhere from six to 10 days.

___

Associated Press writers Seth Robbins in San Antonio and Alan Scher Zagier in St. Louis contributed to this report.

___

This story has been corrected to show that the defense attorneys were at the Monday morning hearing, not that they weren't in attendance.