Officer Matt Murphy was shot four times during a traffic stop on December 1st, 1974.
Authorities delivered a warrant for arrest to Roberto Lopez, who is currently serving a life sentence in an Alabama prison on a separate charge.
Authorities reopened the investigation in January after a prison warden said a "jail snitch" had provided information that implicated Lopez in the shooting.
Several former police officers that worked with Murphy attended a press conference Monday to learn more about the investigation.
After 43 years, Murphy's family and close friends still seek closure.
More than forty years after an Alice police officer was murdered on duty, investigators think they know who pulled the trigger. Authorities say they are a step closer to solving the cold case.
Officer Matt Murphy was shot to death while making a traffic stop in December of 1974. Now 43-years later, authorities have issued an arrest warrant for 70-year-old Roberto Lopez, the man they believe is responsible.
Lopez is already in prison, serving a life sentence in Alabama for armed robbery. Now he faces a capital murder charge. The Texas Rangers and the Alice Police Department reopened the investigation into the murder this January, after a prison warden in Alabama said a "jailhouse snitch" had information that implicated Lopez in the shooting.
"It was a long time coming," Alice Police Chief Rex Ramon said. "I arrived in Alice in 1988, and I never forgot, watching Matt Murphy's plaque at the PD, wondering, when? When?"
The 33-year-old left behind a wife and two young children. Officer Murphy was known for his professionalism, and in the three short years he was with the Alice Police Department, he mad a big impression.
It has been four decades since his death, but the pain of loss is still fresh for those who worked with Murphy.
"I was totally angry," Doroteo Martinez, a former Alice police officer, said. "I wanted to ask questions: who, when, where, and why?"
However, those questions have gone unanswered for former Alice police officers, who worked side by side with Murphy before he was shot to death.
"We want to find out what really happened that night," said former officer Henry Garza.
Police say Officer Murphy made a traffic stop at the intersection of West Main Street and U.S. Highway 281 in Alice when he was shot. During an autopsy a medical examiner recovered four bullets from his body.
Kenneth Helms, a former detective, was one of the first people on the scene.
"I went to him cautiously, and just lifted his head up," Helms said, choking back tears.
Paramedics took Murphy to the hospital where he was pronounced dead.
"The sad part about his death, was all the good that he could have continued doing, that he was taken away from," Martinez said.
By multiple accounts, Murphy's priority was to crack down on drug use and drug dealers. He periodically worked undercover.
Yet those efforts were abruptly halted by four bullets.
After 43 years, Roberto Lopez faces an arrest warrant for capital murder. Murphy's colleagues are now hoping they will finally see justice for their friend, and his family.
"I have always had in the back of my mind a promise that I made to Matt's son when he was a little boy and this happened," Martinez said. "I promised him that this person would be found. And with every anniversary, I always worried more and more, and he always came to my mind. That was the thing that haunted me more than anything else. I had promised the little boy, that something would be done, and you now, he's a grown man now"
District Attorney Carlos Omar Garcia will now work on a case to present to the grand jury in Jim Wells County. If there is an indictment, the next step would be to extradite Lopez to Texas for trial. The DA says it is too early to say whether he will seek the death penalty for Lopez.
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