It's impossible to assassinate President Obama? What if the Secret Service Director decides to join a presidential assassination plot? One of the theories of the JFK assassination is this actually did happen in 1963. The ancient Roman addressed the Senate about Caesar's Praetorian security squads asking, "Who guards the guardians?" In the third century A.D. the Praetorian Guards assassinated emperors in wholesale lots. The Godfather said, "If history has taught us anything, it's that anyone can be killed....even Julius Caesar." There have been four successful assassinations in U.S. history. Abraham Lincoln was shot in the head at Ford’s Theater in 1865 by a confederate sympathizer. James Garfield took two bullets from a preacher in 1881 who waited for the president at a train station in D.C. William McKinley was shot in the belly by an anarchist and died 14 days later from gangrene. And then, of course, Kennedy was tak...