The delicate task of combining volatile chemicals is routine for scientists. Add mental illness, though, and you've got a potentially explosive compound.

So went the saga of Bruce Ivins. The Army microbiologist killed himself after the FBI settled on him as the culprit who sent anthrax-tainted envelopes that killed five people in 2001.

If it were simply a case of one man acting on his private vendettas, maybe this case wouldn't be as troubling. Instead, reports depict Ivins as a severely troubled man who confided his delusions even before the attacks.

Until last fall, Ivins was allowed full access to Army laboratories that contained substances like anthrax. That's a great deal of trust placed in a man who took anti-psychotic and anti-depressant prescriptions and who some colleagues knew to be a "basket case."

Essentially it was like leaving the rabid fox to guard the most precious of hen houses.

History will hardly judge the investigation of the anthrax attacks as textbook law enforcement work. The FBI openly dogged an innocent man, Steven Hatfill, for years, leading him to file a lawsuit that was recently settled for $2.8 million.

If anything mitigates the government's blame, it's Ivins' own cunning. FBI officials suggest he cheated to pass a polygraph test and tossed out misinformation to divert investigators from his scent.

The House and Senate should focus their expected inquiries into how this happened in the first place. Two of their own were among the targets, making this a personal issue for Congress. The Army, too, is following through with a team of experts to re-examine the site's security policies.

Admittedly, with roughly 14,000 researchers handling dangerous biological materials at more than a thousand labs, it's tough to closely monitor the stability of every single person. Yet it's imperative to determine whether a flaw in the system could allow more like Ivins to hang around unchecked.

In the wrong hands, things like anthrax are no longer mere research tools. They're weapons of mass destruction.

The nation's leaders have shown a willingness to go to war on even the suspicion that mad dictators control those weapons. They should certainly be willing to take steps to keep them away from workers proven to be psychologically imbalanced here at home.