In his book, "Contract on America", David Scheim presented evidence that Mafia leaders Carlos Marcello and Santo Trafficante, Jr., as well as organized labor leader Jimmy Hoffa, ordered the assassination of President Kennedy. Scheim cited in particular a 25-fold increase in the number of out-of-state telephone calls from Jack Ruby to associates of these crime bosses in the months before the assassination. According to author Vincent Bugliosi, both the Warren Commission and the House Select Committee on Assassinations determined all of these calls were related to Ruby seeking help from the American Guild of Variety Artists in a matter concerning two of his competitors. The House Select Committee on Assassinations report stated "... that most of Ruby's phone calls during late 1963 were related to his labor troubles. In the light of the identity of some of the individuals with whom Ruby spoke, however, the possibility of other matters being discussed could not be dismissed."