Meanwhile, doctors in northern Virginia said that preliminary tests had found no anthrax in a man who presented himself to a hospital last night saying he had connections with AMI.

CNN: Sources: Anthrax possibly linked to lab

No suspects have been named in the anthrax investigation and no arrests have been made.

CNN: Maryland pond drained in anthrax probe

"There are no indications of anthrax, " a police spokesman told a news conference on Thursday.

CNN: Police calm German anthrax fears