Uber has followed through on threats to fire a star autonomous-car researcher whose hiring touched off a bitter legal fight with Waymo, the former self-driving car arm of Google. Waymo has alleged that Anthony Levandowski downloaded 14,000 documents containing trade secrets before he founded a startup that was purchased by Uber. A federal judge has ordered Uber to return the documents and referred the case to the U.S. Attorney's Office for possible criminal investigation. Uber said in a statement Tuesday that Levandowski missed a company deadline to help with an internal investigation in the case. A telephone message was left Tuesday afternoon for Levandowski.