Fifty years after the JFK assassination there is still speculation about whether Oswald acted alone, but one man insists he has the right answer about what happened in Dallas.

There's no mystery for Gerald Posner, author of "Case Closed: Lee Harvey Oswald and the Assassination of JFK." He says the evidence leads to one inescapable conclusion.

"Fifty years ago, one 24-year-old sociopath, for his own warped motivations, ended Camelot and carried it off without any conspiracy involved," Posner said. 

Posner says we continue to have a fascination with the Kennedy assassination because we're so fascinated with the Kennedy family.