Surveillance footage has emerged of the moment a gang member allegedly killed a 70-year-old off-duty sheriff's deputy with a single punch to the head.
Lawrence Falce died in hospital in San Bernardino two days after being hit by a man named by police as 30-year-old Alonzo Leron Smith at around 11am on New Year's Eve.
Falce, who worked as a cop for 36 years after retiring from the US Army where he completed two tours of Vietnam, was driving in front of Smith when he hit the brakes on his car to avoid two dogs. Smith, who police describe as a 'career criminal', rear-ended him.
The pair then got out of their cars and argued by the side of the road as security cameras at a nearby store filmed them.
After just 50 seconds of arguing, Smith delivered a single punch to the police officer's face, sending him falling backwards onto the sidewalk where he hit the back of his head, police say.
Falce never regained consciousness and died in hospital on Tuesday night.