Crime Stoppers has raised the reward for information in the shooting death of a man in a department store parking lot.
His mother, Rosie Salas, found her only son in his car with two gunshot wounds.
Crime Stoppers said Friday that two donors came forward offering $10,000 each, raising the reward for information leading to an arrest in the case from $5,000 to $25,000.
Dallas police said they need the public's help to solve the case.
"Right now, we don't have any leads that suggest what took place at that time, and we need the help of the community with that," Deputy Chief Sherryl Scott said. "It's been frustrating for us, and it's especially been frustrating for the family because we need to solve this case. We need to know what happened."
Family members told NBC 5 in May that no surveillance cameras recorded the shooting.
Anyone with information can contact Crime Stoppers at 214-373-TIPS(8477) or the Dallas Police Homicide Unit at 214-671-3661. The identity of tipsters will remain anonymous.