Anti-Hillary conspiracy theorist Roger Stone has played a substantial role in Donald Trump’s presidential campaign. Stone — who has been banned from CNN and MSNBC for racist and sexist remarks — once wrote that the idea that the Clintons killed 83 people is “excessive” and that they’re “only plausibly responsible” for half that number. Now, he is claiming that the Clintons killed John F. Kennedy Jr.

Stone has had a long career in political dirty tricks, perhaps starting when he “played a bit part in the Watergate scandal” during the Nixon years. He more recently formed an anti-Hillary group called “C.U.N.T.” and later helped Trump in the Obama birther movement.

Stone was an official Trump campaign staffer until he left last August (both Stone and the Trump camp have competing narratives as to why he departed). But since then, Trump has continued to promote wild claims and conspiracy theories originating from Stone in an attempt to attack Hillary.

In fact, Stone’s friend and former lobbying firm business partner Paul Manafort is now the Trump campaign’s convention manager. Stone and Manafort ran the infamous “Southern Strategy,” which some say is what made Trump’s rise possible.

Most recently, Stone called on Trump’s delegates to sign a loyalty oath and threatened to disclose to the hotels and room numbers of those delegates who switch from Trump to another candidate at the Convention.

While Stone had previously denied that the Clintons killed JFK Jr. (Kennedy died in a plane crash in 1999, which the NTSB ruled was an accident due to pilot error), he said during a recent appearance on a fringe right-wing radio show that his new book will prove the Clintons were involved.

ROGER STONE: I have coming up next year a book which I make the case that John F. Kennedy Jr. was murdered. And he was murdered by the Clintons because he was in the way. Now I have extraordinary new evidence that nobody else has seen.

Listen here, via Media Matters: