A ceremony was held Monday to add the name of police officer Jon Cook to the San Francisco Police Department's Wall of Honor in the city's Hall of Justice. Cook, who was 39, died on the night of June 12 when his police car collided with a second patrol car at 17th and Dolores streets. Three other officers were injured while they and Cook were responding to a call for assistance in arresting a man suspected of assaulting his girlfriend. Cook was the department's first openly gay officer to be killed in the line of duty. His will be the 95th name displayed on the wall that honors police officers killed on the job.