JFK footage released

The theory you mention is one of many alternative explanations about the assassination of President John F. Kennedy. However, the official investigation, including the findings of the Warren Commission, concluded that Lee Harvey Oswald acted alone, firing three shots from the Texas School Book Depository.

The idea that the driver, Secret Service agent William Greer, might have been involved has been widely debunked. Zapruder film analysis and testimonies from eyewitnesses do not support this claim. Greer's actions during the motorcade have been scrutinized, but there's no credible evidence linking him to Kennedy's death.