SINCE THE DEADLY anthrax mailings more than a year ago, the government's public focus has shifted from the crime to measures necessary to combat bioterrorism and make such attacks more difficult in the future. Press briefings concerning progress in the anthrax investigation have given way to government news conferences about rapid response networks, vaccine stockpiles, decontamination research and health worker training. Almost never mentioned is the toll of the attacks on the country: Five persons dead nationwide, including two Washington postal workers, an unprecedented disruption of Congress, interruption of the U.S. Postal Service, and fear and uncertainty throughout the region and nation. This record is all the more disturbing because more than a year after the anthrax was let loose through the mail, U.S. authorities have made no arrests.

The only result thus far seems to be a further deepening of the mystery surrounding the attack. Initial government speculation, which later hardened into an official FBI view, was that the perpetrator was a disgruntled "lone individual," probably someone domestic, with enough of a scientific background to know how to weaponize anthrax spores in a basement laboratory. That view, however, increasingly has been called into question by non-U.S.-government experts. They contend the mailings could not be the work of either an amateur or a loner given the extent of scientific knowledge, technical competence and access to equipment required to convert anthrax spores into such a deadly, finely aerosolized weapon.

Regardless of which theory holds up, the reality is that a person (or persons) committed to launching a bioterrorism attack on the nation is (are) still at large. In that connection, it is hard to know where the Justice Department stands with Steven J. Hatfill, the expert on biological warfare whom investigators have labeled a "person of interest" in the case. Several months ago the government searched Mr. Hatfill's possessions and drove him from his job -- but it still won't call him a suspect, charge him with a crime or clear him. The fact that the government, at this late date, cannot rule out foreign or state-sponsored terrorism, or theft of weaponized spores from an existing biodefense program by a disaffected U.S. scientist, leaves the public further in the dark.

It is somewhat reassuring that in the aftermath of the attacks, we have learned that the treatment of anthrax through the quick and intense use of antibiotics might make this disease less of a killer. The need to solve the crime nonetheless remains urgent. The anthrax menace that was unleashed on the nation claimed five innocent lives, adversely affected the lives of thousands more and nearly brought postal service to a halt. The brutal truth is that he -- or they -- could strike again.