the suspected assassin. >> in the building on the sixth floor we found an area near a window that had partially been blocked off by boxes of books, and also the three spent cartridges fired from a rifle. >> the lieutenant just came out of that building with a british 303 rifle. >> it was a 7.65 mouzer. >> high powered army or japanese rifle of high caliber. >> a 3030 rifle. >> much of the first things you hear are going to be wrong. and to some degree, you are constantly trying to separate out what seemed to be a fact. >> in dallas, a dallas policeman just a short while ago was shot and killed while chasing a suspect. >> j.d.tippit, a good experienced police officer, was shot three times in the chest in the oak cliff section of dallas.