A Slain Florida teenager and the neighbourhood watch captain who shot and killed him exchanged words before the teen punched him in the nose and began banging the mans head on the ground,according to the watch captains account of the confrontation that led to the shooting. The Orlando Sentinel reported that George Zimmerman told police he lost 17-year-old Trayvon Martin in the neighbourhood he regularly patrolled and was walking back to his vehicle last month when the youth approached him from behind. The two exchanged words,Zimmerman said,and Martin then punched him,jumped on top of him and began banging his head on a sidewalk. Zimmerman said he began crying for help; Martins family thinks it was their son who was crying out. Witness accounts differ and 911 tapes in which the voices are heard are not clear. A statement from Sanford police said the newspaper story was consistent with evidence turned over to prosecutors. Meanwhile,Martins parents are blaming police for leaking information about their son being suspended for marijuana and details about the fight he had with Zimmerman that portrayed the teen as the aggressor. Martins mother,Sybrina Fulton,said Monday that it was part of an effort to demonise her son. They killed my son and now theyre trying to kill his reputation.