U.S. Attorney General John Ashcroft says federal officials are pursuing a criminal investigation into anthrax cases in Florida that have left one man dead and two other people contaminated. Federal officials are also trying to calm the public in the wake of the anthrax investigation.

Attorney General Ashcroft appeared on U.S. television and said there is no evidence that the strain of anthrax detected in Florida had been stolen from a laboratory. "We do have the kind of investigation that investigates criminal acts and it is fair to say that it is that kind of investigation," he said. "And we are very concerned and are working very closely with the Centers for Disease Control."

The attorney general also says there is no evidence linking the anthrax cases to the terrorist attacks carried out on September 11.

That message was also delivered to members of Congress Thursday. One of the FBI's top counter-terrorism officials, Tim Caruso, sought to reassure lawmakers and the public that law enforcement is doing all it can to prevent further terrorist attacks.

"There is no need for the American people to panic," Mr. Caruso said. "We are all on heightened alert and understandably react to unusual occurrence in a way we may not have reacted prior to September 11. All of our lives have changed in that sense," he said.

On Wednesday, the FBI announced the creation of a "most wanted" list of international terrorists, a roster containing the names of 22 suspects led by Osama bin Laden.

Attorney General Ashcroft told ABC television that federal investigators are hopeful that the effort to publicize the names of suspected terrorists and the offer of a reward of up to $5 million for their capture will bear fruit.

"I think it is likely that there are terrorists who want to be able to disrupt America," Mr. Ashcroft said. "We have seen Osama bin Laden on television talking about the fact that America would be struck again. I think we have to prepare ourselves and we have to prepare ourselves legally," he said. "We have to do everything possible to interrupt, to disrupt, to make difficult additional terrorist operations.

FBI officials note that previous attempts to target suspected terrorists through "most wanted" lists have had some success. Ramzi Yousef, one of those convicted in the first terrorist attack on the World Trade Center in 1993, was prominently featured on the list prior to his apprehension in Pakistan in 1995.