(NewsNation Now) — A police constable in Texas is pleading for the public’s help to find a man he believes shot and killed an officer this weekend.

“It was a ruthless murder. It was an assassination,” Harris County, Texas Constable Ted Heap said on “NewsNation Prime.”

Houston Police Chief Troy Finner said investigators have identified the accused shooter as Oscar Rosales.

Harris County Precinct 5 Cpl. Charles 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.

“We have video evidence of him shooting our constable,” Finner said during a news conference. He declined to provide more information about the video evidence, citing the ongoing investigation.

Prosecutors have filed a charge of capital murder against Rosales and authorities are offering a reward of $60,000 for information leading to his arrest, said Harris County District Attorney Kim Ogg.

“He is a bold and incredibly dangerous fugitive. He is on the run and somebody out there knows where he is,” Ogg said.

Authorities said that Rosales’ common law wife, Reina Marquez, 40, and his brother, Henri Marquez, 42, have each been charged with tampering with evidence in connection with the case. Court records did not list attorneys for either Henri or Reina Marquez who could speak on their behalf.

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

Heap said the scene was “horrific” and Galloway did not have time to defend himself or call for help.

“It was just something that was premeditated,” Heap said on “Prime.” “There’s no doubt in my mind this individual was ready to take someone’s life if he was encountered that morning and that’s exactly what happened.”

Police believe Rosales is still in Houston, but investigators have evidence that he changes his appearance, Finner said. Authorities were trying to determine if Rosales uses other names. Finner declined to say if the weapon used in the shooting had been recovered.

“We need the eyes and the ears of all of our citizens to help us bring this suspect in custody,” Finner said.

Heap said Galloway had no time to respond or defend himself.

“We will not stop until this individual is apprehended,” Heap said. “We cannot do it without the help of the public.”

Galloway had been with the constable’s office for about 12 and a half years, Heap said. The deputy mentored and trained numerous younger officers, who Heap said were “broken up” over the death.

Galloway is survived by a daughter and a sister, Heap said.