HOUSTON (NewsNation Now) — A man accused of killing a Texas deputy during a traffic stop is being held without bond after being returned to the U.S. from Mexico.

Oscar Rosales, 51, made his initial court appearance in Houston on Wednesday after being captured in Ciudad Acuña, Mexico, just across the U.S.-Mexico border from Del Rio, Texas, on Wednesday morning.

Prosecutors have filed a charge of capital murder against Rosales for the death of Harris County Precinct 5 Cpl. Charles Galloway.

Many details are still under wraps, but Houston’s district attorney Kim Ogg said Rosales has used many different identities and had been wanted under a different name by U.S. authorities since 1996 after not meeting the conditions of his probation following a conviction a year earlier for aggravated assault with a knife.

Authorities were unable to confirm Rosales’ immigration status, but Ogg did confirm that he is wanted for murder in El Salvador.

Investigators say Rosales has been a fugitive in the Houston area for 25 years. Ogg said prosecutors were expected to seek the death penalty in this case. 

“This case has all the ear markings and is a death penalty case,” Ogg said during a news conference. 

The arrest was a joint operation involving Mexican authorities, U.S. marshals, the FBI and the Gulf Coast Violent Offenders Task Force.

Houston Police Chief Troy Finner said he is unsure about the motive behind the shooting, but he is positive they’ve got their guy. 

“No one can speak to sheer evilness … and it’s hard. I’m not even concerned in asking him right now. He did it,” Finner said.

Galloway, 47, was shot and killed around 12:45 a.m. Sunday after pulling over a Toyota Avalon. 

Authorities allege Rosales got out of his vehicle, fired multiple shots at Galloway with some type of assault rifle, and then got back in his car and drove away. Galloway was still seated in his patrol car and attempting to notify dispatch of the traffic stop when Rosales allegedly fired his weapon at the vehicle’s windshield, according to court records.

The shooting was captured on Galloway’s body camera and by dashcam video, according to court records.

Authorities said Rosales’ common-law wife, Reina Marquez, 40, and her brother, Henri Marquez, 42, have each been charged with tampering with evidence in connection with the case.

Both are accused of cleaning Rosales’ car in an attempt to cover up his involvement in Galloway’s shooting death, according to court records.

Rosales’ next court appearance will be Friday morning.