Johnson is accused of beating a 6-month-old shepherd mix with his fist and a 12-pound rock on Nov. 3. The injured dog was taken by its owner to a veterinarian, where it was euthanized.
Investigators say Johnson told them he acted in self-defense and that the dog wounded his wrist and thumb.
Los Angeles County Fire Chief P. Michael Freeman said last month that Johnson has been placed on paid administrative leave.
- Get more local news headlines from Los Angeles
- Have a news tip? Send your tips, video, or pictures