UPDATE (3:29 p.m.): During congressional testimony today, FBI Director Robert S. Mueller III said evidence collected in the agency's investigation of former Army scientist Bruce E. Ivins is strong and backs up their theory that he is the lone culprit behind the 2001 anthrax attacks.

"There was a clear identification of the anthrax in the letters back to being referred or related back to the anthrax that was in the vial in Dr. Ivins' laboratory," Mueller said, in response from a question from Rep. Jerrold Nadler (D-N.Y.) about the strength of the government's evidence. "And that, in and of itself, would give you one means of eliminating others, although, to the extent that there was anthrax that had been distributed from that vial, we traced all of that anthrax and eliminated any other persons who may have had access or utilized that access as a suspect."

Mueller also said the FBI is in dicussions with the National Academy of Science to conduct an independent review of the government's investigation into Ivins.

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FBI Director Robert S. Mueller III is scheduled today to appear before the House Judiciary Committee to defend the government's case against an Army researcher accused of launching a deadly anthrax-by-mail attack in 2001.

The case against Bruce E. Ivins, the Fort Detrick, Md., scientist who committed suicide July 29 before investigators could publicly label him as the lone culprit, has been called into question by a small but vocal group of critics, The Post's Carrie Johnson reports.

Sen. Arlen Specter (R-Penn.), Rep. Rush Holt (D-N.J.), House Judiciary Chairman John Conyers Jr. (D-Mich.) and two other Democrats on the panel and Sen. Charles Grassley (R-Iowa) have signaled their interest in questioning the extent and validity of the FBI's case against Ivins.

Check back for more details about today's hearing, which starts at 10 a.m.