After a grand jury in Ferguson, Missouri, declined to indict Officer Darren Wilson for the shooting death of unarmed teenager Michael Wilson, U.S. Attorney General released a statement reminding everyone that "the Justice Department’s investigation into the shooting of Michael Brown remains ongoing." He emphasized that "the federal inquiry has been independent of the local one from the start, and remains so now."
The Justice Department and the FBI actually have two civil rights investigations, one into whether Wilson violated Brown's civil rights and the other into whether the Ferguson Police Department has a history of racial discrimination. Legal experts don't expect the Justice Department to ultimately file charges against Wilson, though the inquiry into the police department's civil rights history could well lead to mandated departmental reforms.
The Ferguson Police Department also still has its own internal investigation into Wilson's conduct, and Missouri's Department of Public Safety has the right to revoke Wilson's certification to be a police officer. The most likely remaining legal action against Wilson, though, is a possible civil suit filed by Brown's family. The burden of proof in wrongful death or civil rights cases is considerably lower than in criminal cases, and the most Brown's family could hope for is financial penalties and, perhaps, some sense of judicial vindication.