The Justice Department was running into immediate hurdles Monday in its investigation of possible civil rights violations by George Zimmerman in the shooting death of Trayvon Martin -- namely, that after examining the case for more than a year, the evidence has not changed. Though the department announced after Zimmerman's acquittal that it would consider a possible federal case, previously filed FBI documents show agents have not turned up any accounts that Zimmerman, before the February 2012 shooting, exhibited racial bias.