Prosecutors say the killings were orchestrated by Chris Montalvo, who has connections to the Mexican mafia and is the brother of one of the victims. On trial now is one the two men who authorities say attacked the victims on their final day.
Nine years ago, in January 2004, a white Cadillac was discovered in a rural area west of Rosenberg. Inside were two bodies -- Mike Montalvo and his girlfriend Vivian "Michelle" Moreno. Both were shot in the head. For years the case went unsolved. Then detectives determined each was a hit.
Moreno's sister Amy Martinez said, "I'm just glad it's finally here, trying to get it over with."
Martinez says to this day she's not sure what motivated the murders. She's looking for answers.
"Trying to get it over with and get some closure, so they can rest in peace," she said.
Prosecutors say Isaias Santos III did not pull the trigger but that he later told investigators he was in the car that day and that he first tried stabbing Moreno in the head, but couldn't go any further.
"You'll also hear him say that he didn't have the guts to do it, to kill her," prosecutor Bob Yack told the jury.
Investigators say another man in the car, Chris Camacho, fired the gun. The next morning a farmer found Mike Montalvo dead and Vivian Moreno barely alive. She died 12 hours after being flown to a nearby hospital.
Santos' attorney refused comment to us but during testimony has repeatedly questioned whether any scientific evidence places his client at the scene. So far no physical evidence submitted has done so.
Chris Montalvo, the brother of one of the victims, has already plead guilty to murder and is serving a 30 year prison sentence.
The alleged trigger man is still waiting to stand trial for his alleged role in the crimes. If Santos is convicted, he will go to prison for the rest of his life.