The fatal shooting of an unarmed teenager in Florida has prompted protests demanding the arrest of the perpetrator, who says he was acting in self-defence. How much force does the law permit?
On a dark and rainy February night, George Zimmerman sat in his car in Sanford, Florida, a legally-carried 9mm pistol by his side.
There had been a rash of crime in the community, Mr Zimmerman later said, and on that night, the neighbourhood watch volunteer grew wary when a young black man in a hooded sweatshirt appeared.
In a recording of a 911 call released by police, Mr Zimmerman, in his truck, tells a dispatcher that a "real suspicious guy" who "looks like he's up to no good or he's on drugs" was walking through the neighbourhood.
Mr Zimmerman, 28, can be heard huffing and puffing as though he is running, and he tells the dispatcher he is following the person. The dispatcher says: "OK, we don't need you to do that."
Seconds later, a confrontation and a struggle ensued, and a shot was fired. Trayvon Martin, 17, was struck in the chest and died. Mr Zimmerman was detained and questioned by the local police department, then released without charges. He told police Martin had started the fight and that he shot in self-defence.
The incident sheds light on Florida's seven-year-old self-defence law, which critics say is too lenient. The law, nicknamed a "stand your ground" or "shoot first" statute, gives protection from criminal prosecution or civil liability to people who claim self-defence after a shooting or violent incident.