(2003-12-19) -- Democrat presidential candidate Howard Dean today said he believes credible evidence exists to prove that President George Bush knew about airplanes before four of them were commandeered and crashed on September 11, 2001, killing about 3,000 people.

"The most interesting theory I've heard so far," Mr. Dean told a reporter from National Public Radio, "and this can't be proved...is that George Bush knew about airplanes before 9/11. He may have seen them flying overhead in the years before 2001, and some suggest, he may have been a passenger on some airplanes."

Mr. Dean refused to identify the source of his allegation, saying only that the theory was "out there."