Tyler S. Drumheller, a former senior American intelligence official who publicly asserted that President George W. Bush’s administration had knowingly hyped fabricated evidence of Iraq’s arsenal of biological weapons to justify the 2003 invasion, died on Aug. 2 in Falls Church, Va. He was 63.

The cause was complications of pancreatic cancer, his wife, Linda Drumheller, said.

Three years after the invasion and after his retirement from the Central Intelligence Agency, where he had been chief of the European division, Mr. Drumheller took the unusual step of publicly saying that he had warned his superiors that an Iraqi defector who claimed Iraq was equipped with mobile, lethal germ factories was mentally unstable.

Mr. Drumheller also said that before the war, one of Saddam Hussein’s own ministers had confided to American intelligence that the Iraqis had not stockpiled weapons of mass destruction.

“So in the fall of 2002, before going to war, we had it on good authority from a source within Saddam’s inner circle that he didn’t have an active program for weapons of mass destruction?” Ed Bradley asked Mr. Drumheller on the CBS News program “60 Minutes” in 2006.