MADRID — The Justice Department has failed to respond to multiple requests from Spanish authorities for help in an investigation into a local security firm suspected of being used by the CIA to conduct aggressive — and potentially illegal — surveillance of WikiLeaks founder Julian Assange. “I am not so pleased about it,” said Santiago Pedraz, the investigating judge in charge of the case, in an exclusive interview with Yahoo News, when asked about the failure of officials in Washington so far to cooperate with his probe. “They have absolutely not answered anything.”... ...Since June of last year, Spanish judges...