The U.S. Attorney’s Office for the Southern District of New York last week began presenting evidence to a grand jury from a male sex worker who alleged Sean ‘Diddy’ Combs flew him across the country to one of his “freak off” parties, according to people with knowledge of the matter. The testimony from the gigolo lays the groundwork for more criminal charges against the jailed, one-time music mogul, the sources said. In a stunning twist, RadarOnline.com can reveal the grand jury that returned the three-count racketeering, prostitution and sex trafficking indictment against Combs was never dismi…