On August 3, 1948, Whittaker Chambers, a former U.S. Communist Party member, testified under subpoena before the House Un-American Activities Committee (HUAC) that Hiss had secretly been a communist while in federal service. Hiss categorically denied the charge. During the pretrial discovery process, Chambers produced new evidence indicating that he and Hiss had been involved in espionage. A federal grand jury indicted Hiss on two counts of perjury. After a mistrial due to a hung jury, Hiss was tried a second time, and in January 1950 he was found guilty and received two concurrent five-year sentences, of which he eventually served three and a half years.