An 18-year-old allegedly confined to his room by his parents for several years was so malnourished he still had his baby teeth, police told a court.
Mitch Comer was just 5ft, 1in (1.77 metres) tall and weighed only 40kg when he raised the suspicions of a guard at a bus station in Los Angeles last month.
He told police he had been put on a bus by his stepfather Paul Comer on his 18th birthday with a few hundred dollars cash and a list of homeless shelters. Paul Comer told investigators his stepson went to Los Angeles because he wanted to be an actor.
The Georgia teenager said he had been confined to a bedroom and bathroom since being taken out of school several years earlier, police said.
His sisters, aged 11 and 13, who lived in the same house had no contact with him throughout that time.
They thought he had brown hair but never saw him, Paulding County Sheriff's Detective Kyle Shelton said as he gave evidence about his interviews with the family.
"He screams for food and screams to go to the bathroom. That's all (the sisters) know of their brother," he said.
Detective Kevin Morgan testified that the Comers conceded the teen had been confined to the room as punishment.
The rest of the house was filthy and smelled bad, the detectives said, but the bathroom was clean. Mitch Comer told them he cleaned it often to escape boredom.
He was held there for a year before being moved to an adjoining bedroom, where the door was blocked by a fridge. When asked why he did not escape through a window, Shelton said, the teenager replied: "I'm afraid of bugs."
Mitch Comer also told investigators he was fed infrequently, occasionally getting soup or cereal.
He was extremely pale, having been shielded from sunlight, small and still had his baby teeth - the result of malnourishment, Mr Morgan said.
"I thought he was a 12-year-old boy," he added.
Prosecutor Tom Cole called the alleged abuse "one of the most vile and reprehensible acts that the state has seen in a long time".
However, the teenager's mother and stepfather contest many of the allegations.
Paul Comer has said he fed Mitch Comer the same food the family ate, three times a day.
At the hearing, the pair was denied release on bond while authorities investigated why the family had lived at 15 addresses across five states since the late 1990s.