Federal agents are now investigating reports of eight threatening letters with a white substance in five Alabama cities this morning, FBI officials confirmed.



At least one contained an artificial sweetener, an FBI official said.



Angela Tobon, media spokeswoman for the Mobile FBI, said the letters were all mailed to federal offices and "are all the same ...white powder with threatening letters," she said.



None of the letters have tested positive for anthrax, Tobon said.



Dr. Don Williamson, Alabama state health officer, said that the public health laboratory had been notified that it would be receiving samples today from around the state. As for the sample from Birmingham on Sunday, he said "we know that it's not anthrax. We know it's not a biological agent and we know it's not ricin."



"At this point it does not appear to be a toxic substance ... based on the one letter we got out of Birmingham," Williamson said.



Exactly what the white powder in the Birmingham letter was, however, still isn't known, Williamson said. "We hope to know by tomorrow exactly what it is," he said.



Williamson said the state lab got hundreds, if not thousands of samples, to test for anthrax after people died during a nationwide anthrax scare in 2003. But he said a non-agricultural sample has never tested positive in Alabama.



Williamson said the state lab from time to time has gotten threatening letters to test with powdery substances but he can't remember a situation where they received eight in one day.



Few other details about the letters were available from authorities.



One letter was sent to Rep. Jo Bonner's office in in Mobile, and one to his office in Foley, Tobon said. Single letters were sent to the offices of Rep. Mike Rogers and U.S. Sens. Jeff Sessions and Richard Shelby in Montgomery. And one letter was sent to the federal courthouse in Anniston. Another letter also was later reported having also been received in Anniston, an FBI official said.



An official with Rogers' office said that the representative's office in Anniston had re-opened this afternoon.



Stephen Boyd, spokesman for Sen. Sessions, said U.S. Capitol Police asked them to withhold comment pending investigation of the letters. A spokesman for Sen. Shelby referred comment to the FBI.



One letter was received at Birmingham federal offices on Sunday at the Robert S. Vance Federal Building in downtown Birmingham , said Paul Daymond, public affairs specialist with the FBI in Birmingham.



Daymond said the FBI's Joint Terrorist Task Force is investigating the Alabama letters.



Earlier reports from an FBI official in Mobile had indicated possibly two letters were received in Birmingham, but it was only one, the FBI has now confirmed.



Daymond said this afternoon that the powder in one envelope in Anniston tested negative for anthrax. "It was some type of artificial sweetener," he said.



Daymond later reported a second letter was received in Anniston.



The substance at the Vance federal building at first tested positive for anthrax at the scene, but later was determined not to be the sometimes deadly material. The on-scene tests are reliable when the results are negative, but are unreliable when a test is positive, health officials said.



A reward of up to $100,000 was announced today by the U.S. Postal Inspection Service for information leading to the arrest and conviction of the person or persons responsible for the letters.



News Staff Writer Robert K. Gordon contributed to this report.



Latest update: 3 pm. with update on Rogers office

