Federal air marshals kill a passenger on an Orlando-bound American Airlines jetliner after the man claims he has a bomb in his backpack, authorities say. Rigoberto Alpizar bolted down the aisle of American Airlines Flight 924 shortly after 2 p.m. Wednesday. In pursuit behind him, through the narrow passageway of the Boeing 757: his female companion -- police believe it was his wife -- yelling ''stop, stop'' in English and then in Spanish, ``He's sick, he's sick.'' The chaos ended quickly. Federal agents shot the Florida man after he claimed he had a bomb in his backpack. The incident drew...