The victims were simply in the wrong place at the wrong time, according to investigators. They said the gunman and another man were walking on the same side of the street, toward De Leon and his wife, when the gunfire erupted.
One of the men pointed a handgun at the other man and fired several rounds. Police said the suspect missed his target and struck De Leon instead.
De Leon was rushed him to the hospital where later died.
Investigators believe the shooting may have been witnessed by a man driving a yellow bus, possibly a school bus.
Police released a composite sketch of the gunman, described as a black or Hispanic man with a light complexion, between 18-20 years old, 5 feet 11 inches tall, with a slim build. He was wearing a dark-color baseball cap.
Anyone with information was asked to call investigators at (213) 485-4341 or (877) LAPD-24-7.
City News Service contributed to this report.