FBI trying to build legal cases against Russian hackers: sources

WASHINGTON/SAN FRANCISCO (Reuters) - The Federal Bureau of Investigation is intensifying efforts to find enough evidence to enable the Justice Department to indict some of the Russians that U.S. intelligence agencies have concluded are hacking into American political parties and figures, U.S. law enforcement and intelligence officials said on Thursday.Building legal cases is difficult, largely because the best evidence against foreign hackers is often highly classified, they said. Still, some Wh