The FBI believes the terrorist behind the anthrax outbreak in the US may not be a Muslim.
The FBI is preparing to go public with what its scientists have learned about who is behind the anthrax letters in the hope of getting more information from the public.
Many investigators believe the suspect is an educated, mature male, "not a Muslim", and "likely born in the United States," CBS Newsreports.
Mr Gregg McCrary, a former FBI profiler, said although the FBI has not rejected the idea the sender may be a terrorist associated with Osama bin Laden, that is not the main theory.
"They're also looking at the possibility of a home-grown individual, maybe the loner paranoid type of individual as well who may be doing this," he said.
FBI handwriting and linguist experts say they have also concluded that the mis-spelling of "penicillin" in two letters, plus the words "can not" in another was deliberate.
They will point to the awkward way in which the numeral "1" is written, the numerous deletions and the dashes in the September 11 date as a distinctive writing style that someone may recognise.
PA