The anthrax was mailed from Trenton, New Jersey, but the FBI has no evidence that Ivins was in Trenton on the days the envelopes were mailed. Even if Ivins was involved, why would the FBI close the investigation if the possibility remains that he wasn't working alone?

Answering these unanswered questions should be a priority if the FBI wants us to believe it's done its job. That means providing a degree of detail that's so far missing from public disclosures.

In the summary of its findings, the F.B.I. states that investigators used four different genetic techniques to match the anthrax-laced attack letters to a unique DNA footprint of a single anthrax spore preparation in one flask that had been in Dr. Ivins’s custody.

Sounds reasonable. Yet the investigators present no details on the scientific methods they used to make this match or how they employed them. That’s a problem, because without such detail it is hard to tell if they specifically ruled out a similar match between the anthrax in the letters and anthrax preparations with the same DNA footprint kept at a number of other labs around the country. The basic methods of genetic analysis are well known. Why not provide enough detail about their procedure to enable other scientists to tell whether they could actually single out Dr. Ivins’s spore preparation as the culprit?

Andrews points to other unanswered questions raised by the public record:

First, isn’t it possible that the manipulation of the contents of the anthrax letters in Dr. Ivins’s laboratory might have contaminated the work environment enough to potentially jeopardize the integrity of subsequent samples taken from the lab? Might that perhaps explain why the anthrax powder used in the attacks was later found to have the same DNA footprint as the other anthrax preparations in Dr. Ivins’s lab? At the very least, wouldn’t this call his guilt into doubt?

If we're supposed to feel assured that FBI analysts completed a sound scientific investigation, we should all be worried. This is the agency that couldn't even get a fingerprint match right in Brandon Mayfield's case. This wouldn't be the first time the FBI cooked the science in response to pressure to solve a crime.

We can't feel secure in our homeland until the FBI releases detailed evidence that independent scientists can review. Until that happens, we can't know whether the FBI got it right in pinning the anthrax plot on Ivins alone.