Corrected: U.S. investigators probing years of WikiLeaks activities - sources

U.S. investigators pursuing a long-running criminal investigation into WikiLeaks and its founder Julian Assange have dug into the website's activities going back years, people who have been in contact with witnesses in the case say.American investigators are gathering information and pursuing witnesses involved in both recent WikiLeaks disclosures and the website's large-scale postings of U.S. military and diplomatic messages over several years from 2010.Officially, U.S. authorities have issued