Ivan Sanchez, 23, was sentenced Friday to 50 years to life for the 2011 killing of Esteban Navarrette, whom Sanchez had mistaken for a patron he had been arguing with earlier.
Orange County prosecutors said Sanchez and two friends had exchanged words with another customer at the Santa Ana restaurant in February 2011, over which state in Mexico was the better place.
The trio left the restaurant to fetch a handgun and returned to settle the argument. They confronted the 35-year-old Navarrette and his wife in the parking lot.
Navarrette told Sanchez he was not the man he was looking for, but Sanchez shot him in the head anyway.
The Los Angeles Times said Sanchez's two co-defendants pleaded guilty to murder or manslaughter charges and received stiff prison sentences this fall.