According to Michael C. Piper in Final Judgment: The Missing Link in the JFK Assassination Controversy, Israeli Prime Minister David Ben-Gurion orchestrated the assassination after learning that Kennedy planned to keep Israel from obtaining
nuclear weapons.
Michael C. Piper claimed the assassination "was a joint enterprise conducted on the highest levels of the CIA, in collaboration with organized crime — and most specifically, with direct and profound involvement by the Israeli intelligence service, the Mossad. Piper also alleged that Jewish mobster Meyer Lansky and the Anti-Defamation League (ADL) were linked to the murder. The ADL responded with harsh criticisms, called the claims ridiculous, and denounced Final Judgment as ... antisemitic.

Piper also wrote articles in American Free Press which alleged that the Mossad and the FBI conspired to set up the assassination of Martin Luther King Jr. Piper claims this was motivated by fear of King's anti-Israel statements combined with his massive grassroots power.

Piper's body was discovered on May 31, 2015 at the Budget Saver Motel in Coeur d'Alene, Idaho.