MELISSA BLOCK, host:

From NPR News, this is ALL THINGS CONSIDERED. I'm Melissa Block.

We begin this hour with the latest in the case of scientist Bruce Ivins and the 2001 anthrax killings. Government sources tell NPR that the FBI plans to reveal part of its case against Ivins tomorrow. However, the FBI will not close the investigation, which means it's not over yet.

Bruce Ivins is the microbiologist who prosecutors believe sent anthrax through the mail to news outlets and members of Congress in 2001. He committed suicide last week, and his lawyer maintains he was innocent.

NPR has a team of reporters working on this case. Our justice correspondent Ari Shapiro is among them. And Ari, why don't you bring us up to date on what will be happening tomorrow.

ARI SHAPIRO: Well, there are going to be two events that will probably take place simultaneously. In one of them, FBI director Robert Mueller will brief victims and their family members in private. The other event will be a public event where members of the FBI Washington field office will say that they're moving toward closing the case, but they're not going to close the case, and they will reveal some but not all of their evidence against Bruce Ivins.

BLOCK: Now, this decision not to close the case, what's going on there?

SHAPIRO: Well, apparently they've found some new stuff in the last week or so. There are affidavits that the FBI cannot unseal because it has new information in it that the FBI has yet to pursue. And remember, this is a seven-year-old case, so the fact that they're still pursuing new information shows you just where this investigation was. It was not done when Bruce Ivins killed himself.

The FBI, according to sources, had not met to discuss plea bargains with Ivins. They had hoped to persuade him to turn himself in and confess, but they were by no means at the end of their investigation yet.

BLOCK: What have you learned about what kind of evidence the FBI has gathered against Bruce Ivins?

SHAPIRO: It's a combination of forensic and circumstantial evidence. Sources tell us there are no eyewitnesses who can exclusively finger him as the culprit. But he was apparently one of about 10 people who had access to the strain of anthrax that was used in the attacks.

We spoke today with somebody who worked at the lab with him, a man named Jeff Adamovicz, who tells us Ivins had access to a freeze-dryer that could have dried out the spores, so that they could have been sent through the mail. But Adamovicz also said the FBI did tests on that machine and did not take it away, so they may not have considered it a key piece of evidence.

Apparently, the FBI also is relying on logs that show that just before the letters were sent, Ivins was at the lab late at night, on weekends alone, and other times that may have been - you know, suggested that he was doing something he didn't want people to know about. And then they're also going to reveal some information about what one source described as a messy personal life.

BLOCK: And what would the relevance of that be, what sort of thing in his messy personal life might be tied to this investigation?

SHAPIRO: Well, it might not incriminate him per se, but it could undercut the portrait that friends, family members, coworkers are painting of him as an upstanding scientist, an all-around good guy, for example.

Apparently, he had a post-office box under an assumed name. He also had a kind of unusual interest in a sorority called Kappa Kappa Gamma. And the executive director of that sorority put out a statement today saying the FBI has contacted the sorority to ask about what they called contacts between Dr. Ivins and some chapters and members of Kappa Kappa Gamma for more than 30 years.

He may have been particularly interested in a chapter of the sorority in Princeton, New Jersey, which could help explain why this guy, who lived near Washington, D.C., may have mailed these anthrax letters from post offices in New Jersey. We should say, though, that at least one source close to the investigation says Ivins took and passed a couple of lie detector tests on this issue. That could be why he was allowed to maintain his security clearances while this investigation was going on.

BLOCK: Ari, I gather you've been fleshing out the biography of Bruce Ivins. What have you learned?

SHAPIRO: Yes, going all the way back to Lebanon, Ohio, where he went to high school. I actually found his high school yearbook photo from 1964. We posted that on npr.org, so you can look at it there. And I contacted the director of his senior class play. The play was called "The People vs. Maxine Lowe." And the director, Joe Haven(ph), told me it was a murder mystery in which he cast Ivins as the murderer.

BLOCK: A lot of ifs still remaining here, Ari - a confusing case, and it seems like a lot of questions unanswered at this point.

SHAPIRO: One big question: What was his motive, if he did carry out these attacks? Another big question: Given that the key suspect has now died, how confident is the government that he was their man? I mean, you may remember a few years ago the FBI had circumstantial evidence that appeared to implicate a different scientist, Steven Hatfill. The FBI was totally wrong on that. Hatfill was innocent and the FBI ended up paying him millions of dollars.

So, today, people are asking, if Hatfill had committed suicide those years ago, would the FBI have closed the case and considered it done when they had the wrong guy?

BLOCK: Maybe some answers tomorrow. NPR's Ari Shapiro, thanks so much.

SHAPIRO: You're welcome. Transcript provided by NPR, Copyright NPR.

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