A Florida judge has rejected a bid by George Zimmerman to delay his June trial for the murder of the unarmed African-American teenager Trayvon Martin. Zimmerman could face up to 25 years in prison if convicted of second-degree murder after shooting Martin dead in Sanford, Florida, one year ago this month. Zimmerman, who claims he shot Martin in self-defense, was not charged in the killing until months later following nationwide protests calling for his arrest. Meanwhile, supporters across Florida mourned Martin on Tuesday, the day he would have turned 18 years old.