George Zimmerman, a white hispanic, spotted the teenager while he was walking back to his father's girlfriend's house after having bought sweets and iced tea.
The neighbourhood watchman called the police to report a "suspicious guy" and followed Martin despite the force advising not to.
Neighbours said they heard a scuffle, cries for help and then a gunshot. Martin was on the phone to his girlfriend at the time of the incident and she heard his running account of being followed and then trying to get away from Zimmerman.
The case of the shooting of unarmed black teenager Trayvon Martin may have shocked America, but it is not an isolated incident.
President Obama has said the killing of an unarmed black teenager by a neighbourhood watch officer is a 'tragedy.'
The parents of Trayvon Martin are demanding justice after the unarmed teenager was shot dead in Florida by a neighbourhood watch guard.