ABC News | September 17, 2008
By Jason Ryan

Senate Judiciary Committee chairman Sen. Patrick Leahy told FBI Director Robert Mueller during testimony before his committee that he did not believe Army scientist Bruce Ivins acted alone in the 2001 anthrax attacks.

"I believe there are others involved, either as accessories before or accessories after the fact," said the Vermont Democrat who received an anthrax-tainted letter. "I believe that there are others out there. I believe there are others who could be charged with murder."

Mueller had testified earlier that, after reviewing the case file, he was convinced beyond a reasonable doubt that Ivins was the sole actor in the anthrax mailings that killed five people and sickened others.

"We have looked at every lead and followed every lead to determine whether anybody else was involved, and we will continue to do so," Mueller told Leahy.

During the last two days of testimony, Mueller asserted that the FBI's case against Ivins was solid. Ivins committed suicide in July, and the FBI and Justice Department have released numerous documents relating to the case that suggest Ivins was the anthrax attacker.

A key part of the case rests on the scientific comparison of anthrax Ivins used and anthrax that was mailed. The FBI also has released information that shows Ivins spent numerous hours alone in one of the biohazard suites at Fort Detrick in the months and days before the anthrax mailings.

Mueller has said the FBI will work with the National Academy of Science to have an independent review on the case.

When Leahy asked whether anthrax was produced at other locations besides defense contractor Battelle Ohio and at the military's Dugway Proving Ground in Utah, Mueller confirmed that there were 15 labs in the United States and three overseas that had the ability to produce the Ames strain.

"It should be a concern of all Americans that biological weapons were used on the Congress and the American people," Leahy said.

Sen. Chuck Grassley, R-Iowa, also pushed for the FBI to release more information on the investigation, noting, "Given all the time and money sunk into this investigation, I believe the American people deserve more than just a press conference and a few briefings."