The FBI official in charge of the probe into the deadly 2001 anthrax mailings said the investigation still has top priority among the bureau’s unsolved cases, but he acknowledged the anthrax sender may never be caught.
“Despite our very, very, very best efforts, we still might not be able to bring it home,” said Assistant Director Michael A. Mason, who heads the FBI’s Washington field office, which is investigating the case.
“This would not be the first case in the FBI’s history that remained unsolved,” he said. “It simply happens to be the first case that has received this level of publicity that has not yet been solved.”
Mr. Mason said FBI Director Robert S. Mueller III continues to receive weekly briefings on the probe 28 months after the mailings. “I would say the anthrax case is the director’s number one priority,” he said. “This is a case the director feels we must solve — period.”
In a meeting Friday with reporters from The Washington Times, Mr. Mason discussed the anthrax probe as well as the investigation into this month’s discovery of poisonous ricin in the office of Senate Majority Leader Bill Frist, Tennessee Republican.
Investigators continue to sort through letters from Mr. Frist’s mailroom, he said. He dismissed reports that the substance had not been ricin but rather a harmless paper byproduct.
“That’s not the case,” Mr. Mason said, adding that he had received confirmation from the chief FBI scientist Friday that the substance was ricin. “We did not shut down the whole of government for envelope droppings.”
Although the ricin case “remains a mystery,” Mr. Mason said, there was “no apparent linkage” to the anthrax attacks, in which deadly spores of the bacteria were mailed to senators on Capitol Hill and to news outlets in Florida and New York in the weeks after the September 11 hijackings.
Mr. Mason has said leaks to reporters about the anthrax case were damaging. He spoke cautiously about the investigation into the poisoned letters, which caused five deaths in October and November 2001.
“We have strict instructions as far as what not to talk about as far as anthrax goes,” said Mr. Mason, who took over the investigation last year after Van A. Harp retired as head of the Washington field office.
Mr. Mason said he couldn’t discuss an anonymous letter received by the FBI in the weeks before the anthrax attacks, which accused an Egyptian-born scientist at the Environmental Protection Agency of plotting biological warfare against the United States.
The Times reported last week that the FBI recently had questioned at least one other EPA scientist about the anonymous letter, which accused EPA toxicologist Ayaad Assaad of being a religious fanatic with the means to use bioterrorism weapons.
Asked whether the FBI was investigating any connection between the anthrax mailings and the anonymous letter, Mr. Mason told The Times: “I just can’t talk about that. I can’t talk about that letter.”
Pressed about the significance of the anonymous letter, given to the FBI after it had been sent to police in Quantico, Va., in October 2001, Mr. Mason said flatly that “the letter is not a priority.”
Mr. Assaad developed a ricin vaccine at Fort Detrick, Md., and is regarded as one of the top U.S. authorities on ricin.
Mr. Mason said the leading theory in the ricin probe is that the toxin — which is derived from the castor bean plant — was mailed to Mr. Frist’s office, although investigators have yet to identify an envelope in which it might have been mailed.
He said FBI agents working jointly with U.S. Capitol Police still are searching for any connection between the ricin found in the Senate leader’s office and other letters containing ricin discovered last year, one at a Greenville, S.C., postal facility in October and another sent to the White House in November.
Those letters were signed by “Fallen Angel,” who said he was angry about new federal laws regulating truckers’ driving hours.