The suspect, 18-year-old Kristian Gonzalez, pleaded not guilty. He surrendered around noontime Tuesday and is due back in juvenile court on February 25.
His attorney asked for isolation because both he and his client have received a number of threats.
The incident occurred in December on Rosa Parks Boulevard and Van Houten Street, but the brutal violence had people living in the community afraid to go outside and frustrated.
Police called the attack disgusting, saying the suspect was being sought even after it became clear he intended to surrender.
Attorney Harley Breite doesn't deny his client is the one on video being encouraged to throw the first and only punch, but he says the clip is only a few seconds and cites Gonzalez's mental health history as a possible factor. He also ask for a psychological and medical review on Gonzalez and that he continue his medications.
As for the victim, he was treated at a hospital after the knockout punch and released.
Gonzalez was 17 when the video was recorded, so he's charged with second-degree aggravated assault and endangering an injured person as a juvenile.
Police Director Jerry Speziale released a video statement Friday on Facebook to the public about the video.
The 16-year-old who allegedly shot the video surrendered to police over the weekend. His name has not been released because of his age.