Former Army scientist Bruce Ivins committed suicide last month, as the FBI prepared to charge him in the attacks.
Daschle said the FBI’s case against Ivins is convincing, but in an interview, he told the AP he is not completely persuaded that the investigation focused on the right person and said the evidence in the case should be scientifically reviewed.
The Los Angeles Times conducted their own review of evidence recently, concluding that the FBI missed many early signs linking Ivins to the attacks.
Both Daschle and current Senate Judiciary Committee Chairman Patrick Leahy received anthrax-laced letters in their Senate offices in 2001.
Daschle, Leahy and Rep. Rush Holt have all been briefed by FBI director Robert Mueller on the evidence against Ivins.
Mueller is set to testify before Leahy's committee on Sept. 17, where the anthrax investigation will surely come up.