Florida rally: Trayvon Martin death 'a travesty of justice'

The shooting of an unarmed teenager has sparked peaceful demonstrations in Florida against what has been called 'a travesty of justice'.

17-year-old Trayvon Martin was killed by a self-appointed town watch patrolman more than three and-a-half weeks ago in Sanford.

When Trayvon Martin was killed in February, police declined to charge George Zimmerman, who claimed he fired in self-defence.