Killer of unarmed black teenager called police 46 times in a year

Trayvon Martin was shot dead as he returned from buying sweets for his brother

The vigilante who shot Trayvon Martin, an unarmed black teenager whose killing has sparked outrage, had called police to the gated community where he lives 46 times in the previous year, it emerged yesterday.

George Zimmerman, a neighbourhood watch leader and gun enthusiast with a chequered past, repeatedly called emergency services when he spotted people he thought "suspicious" at The Retreat at Twin Lakes in Sanford, Florida. He was particularly worried about African-American youths wandering in the grounds. Recordings of six of Mr Zimmerman's most recent calls were released by the sheriff's office; in four of them, the "suspect" was a black male.

On 26 February, Mr Zimmerman, 28, approached Trayvon, 17, who was wearing a hoodie as he walked to the Twin Lakes home of his father's girlfriend, having visited a 7-Eleven store. After a brief confrontation, the teenager was shot. He was found dead, unarmed, with a bag of Skittles and an iced tea. Police did not arrest Mr Zimmerman, apparently accepting his claim that he acted in self-defence. The US Justice Department has asked the FBI and civil rights department to review the case. A grand jury is also investigating.

More than a million people have signed a petition calling for Mr Zimmerman to be charged with murder. Trayvon's parents, Sybrina Fulton and Tracy Martin, were expected to attend a rally in his memory – called the Million Hoodie March – in Union Square, New York City, last night.

Civil rights activists have already held demonstrations across Florida, noting that Trayvon's death followed two other incidents in which Sanford police were accused of failing properly to investigate attacks on black men by white suspects.

Public pressure intensified as more became known about the background of Mr Zimmerman, who is in hiding with his family after death threats. Unlike Trayvon, who had no criminal record, Mr Zimmerman has had several run-ins with the law. In 2005, he was arrested for allegedly assaulting a police officer at a bar. Later that year, he was accused of domestic violence.