The two men identified themselves as pilots when they came to the emergency room of Holy Cross Hospital in Fort Lauderdale last June.
One of them had an ugly, dark lesion on his leg that he said he developed after bumping into a suitcase two months earlier. Dr. Christos Tsonas thought the injury was curious, but he cleaned it, prescribed an antibiotic for infection and sent the men away with hardly another thought.
But after Sept. 11, when federal investigators found the medicine among the possessions of one of the hijackers, Ahmed Al Haznawi, Tsonas reviewed the case with investigators and arrived at a new diagnosis: that Al Haznawi's infection was consistent with cutaneous anthrax, which produces skin lesions like the one Tsonas treated.
Tsonas' assertion, first made to the FBI in October and never revealed publicly, has added another layer of mystery to the investigation of last fall's deadly anthrax attacks, which has yet to focus on a specific suspect.
The possibility of a connection between the Sept. 11 attacks and the subsequent anthrax-laced letters has been explored by federal authorities since the first anthrax cases emerged in early October. But a recent memo, prepared by doctors and biological weapons experts at the Johns Hopkins Center for Civilian Biodefense Strategies, and circulated among top government officials, has renewed a debate about the evidence.
The group, which interviewed Tsonas, concluded that the diagnosis of cutaneous anthrax, was "the most probable and coherent interpretation of the data available." The memo added that: "Such a conclusion of course raises the possibility that the hijackers were handling anthrax and were the perpetrators of the anthrax letter attacks."
In their public comments, federal officials have said that they are focusing largely on the possibility that the anthrax attacks were the work of a domestic perpetrator. They have hunted for suspects among scientists and others who work at government laboratories, or contractors, that handle germs.
The disclosure about Al Haznawi, who died on United Airlines Flight 93, which crashed in Pennsylvania, sheds light on another front in the investigation. Senior law enforcement officials said that in addition to interviewing Tsonas in October and again in November, the FBI scoured the cars, apartments and personal effects of the hijackers for evidence of anthrax, but found none.
And in October, a pharmacist in Delray Beach, said he had told the FBI that two of the hijackers, Mohamad Atta and Marwan Al-Shehhi, came into the pharmacy looking for something to treat irritations on Atta's hands.
If the hijackers did have anthrax, they probably would have needed an accomplice to mail the tainted letters, according to bioterrorism experts knowledgeable about the case. The four recovered anthrax letters were postmarked Sept. 18 and Oct. 9 in Trenton, N.J. It is also possible, experts said, that if the hijackers had come into contact with anthrax, it was entirely separate from the supply used by the letter sender.
For his part, Tsonas said he believes the hijackers probably did have anthrax.
"What were they doing looking at crop-dusters?" he asked, echoing expert fears that the hijackers may have wanted to spread lethal germs. "There are too many coincidences."
In recent interviews, Tsonas, an emergency room doctor, said Al Haznawi came into the hospital early one evening in June 2001, along with a man who federal investigators believe was another hijacker, Ziad Jarrah, believed to have taken over the controls of United Airlines Flight 93. Jarrah, he said, "had to take the initiative, in that the other's English skills were marginal."
They used their own names, he added, not aliases.
The men explained that Al Haznawi had developed the ulcer after hitting his leg on a suitcase two months earlier. Tsonas recalled that Al Haznawi appeared to be in good health, and that he denied having an illness such as diabetes that might predispose him to such lesions. The wound, he recalled, was a little less than an inch wide and blackish, its edges raised and red.
Tsonas said he removed the dry scab over the wound, cleansed it and prescribed Keflex, an antibiotic that is widely used to combat bacterial infections but is not specifically recommended for anthrax.