Piper claims John F. Kennedy's assassination "was a joint enterprise conducted on the highest levels of the CIA, in collaboration with organized crime &...the Israeli intelligence service Mossad." In his underground best-seller, Final Judgment, he posits that Israeli prime-minister David Ben Gurion was the prime mover in his assassination. It was due to disputes with Palestine & Egypt, plus Kennedy's attempts to halt Israeli atomic research. This theory also seeks to tie in other Kennedy assassination theories, primarily involving Jewish mobster Meyer Lansky's organizing the hit, & future president Lyndon B. Johnson staging the event from inside the administration. He also alleged that the Anti-Defamation League also was linked to the murder. The ADL responded with harsh criticisms, called the claims ridiculous & denounced Final Judgment as anti-Semitic.
Additionally, Piper has written articles in American Free Press claiming that Mossad & the FBI conspired to set up the assassination of Martin Luther King, Jr. This was motivated by fear of King's anti-Israel statements combined with his massive grassroots power.