Scott Thorson, once Liberace's much younger boyfriend, claimed he had an affair with the late Michael Jackson, The Daily Mail reported June 7.Thorson's memoir Behind the Candelabra tells the story of his 6-year relationship with Liberace, which started when Thorson was 17 and the entertainer was 57. The book is the basis for the upcoming HBO movie of the same name.Thorson, 54, said Liberace introduced him to Jackson in the late 1970s, according to The Sun.