There seems to be a deliberate process of leaks going on ahead of any possible "case closed" press conference. This is just in from the NYT:

Dr. Ivins, who had a history of alcohol abuse, had for years maintained a post office box under an assumed name that he used to receive pornographic pictures of blindfolded women.

Years ago, he had visited Kappa Kappa Gamma sorority houses at universities in Maryland, Virginia and West Virginia, an obsession growing out of a romance with a sorority sister in his own college days at the University of Cincinnati — although someone who knew him well said the last such visit was in 1981.

I think it's important to remember that Ivin's character is not the issue here. Even if he was a sleazy pervert, as the Feds seem to be trying to establish, that doesn't make him guilty. Conversely, even if he is innocent that does not make him a saint (he may have been a willing member of the Camel Club's anti-Arab harrassment, for example).

The NYT article also notes some more disturbing elements of the investigation:

They had even intensively questioned his adopted children, Andrew and Amanda, now both 24, with the authorities telling his son that he might be able to collect the $2.5 million reward for solving the case and buy a sports car, and showing his daughter gruesome photographs of victims of the anthrax letters and telling her, “Your father did this,” according to the account Dr. Ivins gave a close friend.

As the investigation wore on, some colleagues thought the F.B.I.’s methods were increasingly coercive, as the agency tried to turn Army scientists against one another and reinterviewed family members.

One former colleague, Dr. W. Russell Byrne, said the agents pressed Dr. Ivins’s daughter repeatedly to acknowledge that her father was involved in the attacks.

“It was not an interview,” Dr. Byrne said. “It was a frank attempt at intimidation.”

Dr. Byrne said he believed Dr. Ivins was singled out partly because of his personal weaknesses. “They figured he was the weakest link,” Dr. Byrne said. “If they had real evidence on him, why did they not just arrest him?”

Another former co-worker, Dr. Kenneth W. Hedlund, who collaborated on anthrax research with Dr. Ivins in the 1980s, had a similar theory.

“The investigators looked around, they decided they had to find somebody. They went after all of them but he looked the most susceptible to pressure,” Dr. Hedlund said. “It is like prisoners of war: if they are harassed enough, they will be driven to do anything. But I don’t believe he would have done what they say he did.”

But I guess the really critical part of the NYT article is the scientific explanation, which goes pretty far:

F.B.I. officials say they do know a great deal about what happened and will make it public, possibly as early as Wednesday. They say the core of their case will be the science, which produced the giant step from a globe of possible suspects to a single lab and a single flask...

Further, the attack strain contained bacteria with both the flipped and the unflipped DNA, showing that it was a mixture of two strains, which analysts later found reflected a mix of origins — 85 percent from the Dugway Proving Ground of the Army in Utah and 15 percent added at Fort Detrick, according to one person close to the investigation.

To make sure the case for the distinctive features of the attack anthrax could hold up in court, agents collected thousands of samples of Ames strain anthrax from labs around the world, said scientists familiar with the F.B.I.’s thinking. “This is the step that took so long,” one scientist said.

There's a lot more scientific stuff in the article, linked at my moniker below.

This NYT article still does not establish Ivin's guilt in any way. I'd be interested to see if they think they can prove he sent the Quantico letter, if they are going to keep ignoring that part of the case.