"The mysterious case of Dr. David Graham, a dentist in Shreveport, Louisiana. Graham said that he had met three of the 9/11 hijackers a year before the attacks at a home in Shreveport. He became suspicious of them (he thought they were planning attacks on nearby Barksdale AFB) and contacted the FBI.
The man who hosted the hijackers in Shreveport was a Pakistani named Jamal Khan. In 2004, Khan pled guilty to hiding cash transfers to Pakistan, and in an unusual plea deal the government stated that nothing in this deal would absolve Khan from any future prosecution regarding the attacks of September 11.
Dr. Graham apparently met Khan in conjunction with the 9/11 conspirators and was set to testify against him at a deportation hearing sometime in 2004, following Khan's conviction on the money transfer charge. He was also trying to publish a manuscript about meeting the three men and his contacts with the FBI.
Then, Dr. Graham fell seriously ill from what his family says was poison. Shortly thereafter, Jamal Khan disappeared.
David Graham R.I.P."