his niece said she does not know if lee harvey oswald acted alone in the killing. that's just the kind of speculation that has kept conspiracy theorists busy for a half century. senior political analyst brit hume has some thoughts on all this tonight. good evening, brit. >> hi, bret. when the night club owner jack ruby shot accused kennedy assassin lee harvey oswald to death in a dallas police department hallway he ended more than oswald's life. he ended any chance that the case that oswald had killed kennedy and done so alone would ever be tested in a court of law. the blue ribbon commission led by then chief justice earl warren has proved a poor substitute. reams of material pointing in a multitude of directions have given rise to a welter of alternate theories of the kennedy murder. some say the cia was behind it. some say lyndon johnson was. others say the mob did it. my personal favorite is the one propounded by a british writer who continued in a book called the oswald files that the murder was actually carried out by a