At least four key witnesses have changed their stories about what they saw the night George Zimmerman fatally shot Trayvon Martin in Sanford, Fla., the Orlando Sentinel reported Tuesday. The report comes after state prosecutors released about half the evidence they have in their second-degree murder case against Zimmerman. The witnesses, known publicly only by numbers, first talked to Sanford police and later to the Florida Department of Law Enforcement and state prosecutors Witness 2: A young woman from the Retreat at Twin Lakes community, where Martin, 17, was shot Feb. 26, first told investigators she saw two men running...