Cyntoia Brown was sentenced to life in prison in 2004 for shooting dead Johnny Allen, a 43-year-old Nashville estate agent who picked her up for sex.
The teenager who went home with Mr Allen that night had been repeatedly raped and beaten. She was on the streets by order of her boyfriend, described as a violent, drug-addled pimp named "Kutthroat", who she said verbally abused her and made her strip at gunpoint. He had demanded that she make him some money.
