Sean Sidi, 19, of San Francisco was last seen May 21, 2013 after visiting a former teacher at the French American International School. Surveillance captured him leaving the school on foot at about 11:40 a.m. He spoke with his father around 1:30 p.m., saying he planned to take a bus to Golden Gate Park. His phone last pinged near the park at 2:00 p.m., and all communication stopped after that.

Six months earlier Sean had suffered a traumatic brain injury and undergone surgery to replace part of his skull. At the time he went missing he was wearing a black splint on his left arm, and his family has emphasized that even a minor head injury could have serious consequences without ongoing care. Despite searches and law enforcement efforts, no substantial leads have emerged.

If anyone was in or around Golden Gate Park on May 21, 2013 and saw Sean or remembers someone matching his description, please come forward with information.