It began with an ugly red bump on the middle finger of Johanna Huden's right hand. Huden, an editorial assistant for the New York Post, thought it was an insect bite.

In retrospect, Huden's infection, which appeared about Sept. 21 last year, would turn out to be the first sign of the first major bioterrorist attack in U.S. history. Her job opening the Post's mail had put her in contact with spores of Bacillus anthracis leaking from a poisoned letter to the editor - making her what epidemiologists call the "index case" of the anthrax outbreak.

The attacks turned the daily mail into a lethal weapon, killing five people and sickening at least 17 others, some of whom suffer lingering fatigue and other ailments a year later. Scientists have discovered how little they really knew about anthrax, considered until recently chiefly a threat to cattle in Third World countries. And the federal government has begun to pour billions of dollars into defense against bioterror - though some critics wonder whether the boom in germ studies might actually make the country less safe.

But even as the anthrax attacks have set off a scientific gold rush, the extensive criminal investigation that began a year ago this week has failed to identify the perpetrator. Despite the combined resources of the FBI and the Postal Inspection Service, the investigation has been widely criticized for unaccountable delays and questionable investigative methods.

In November, investigators knocked down the door of a house in Chester, Pa., shared by the city's health commissioner and director of lead-poisoning prevention, and conducted a 13-hour search in biohazard gear. The two officials, Drs. Irshad and Masood Shaikh, and city accountant Asif Kazi, all Pakistani natives, were questioned at length by FBI agents. Nothing more has happened, but an FBI spokeswoman says the investigation of the Shaikh brothers and Kazi "is still ongoing."

More recently, investigators have wound up in a public standoff with biodefense expert Dr. Steven J. Hatfill. With agents following him around the clock and conducting much-publicized searches of his former Frederick apartment, Hatfill has mounted a counter-campaign, saying the pursuit has destroyed the career and reputation of an innocent man. The FBI still appears to be focused on Hatfill, but the bureau has never named him as a suspect or made public any evidence linking him to the attacks.

For Huden, whose cutaneous anthrax infection left only a mottled scar on her finger, the FBI's failure to solve the anthrax case is frustrating and alarming.

"It's shocking that with so many agents, they couldn't find what's going on right here on U.S. soil," she says. "There's no closure to it. You don't know who did it. You don't know if they could do it again."

'We don't have a clue'

Experts who have watched the investigation unfold are beginning to wonder if the attacker will ever be identified.

"A year later it appears that collectively we don't have a clue," says David Siegrist, who studies bioterrorism at the Potomac Institute for Policy Studies in Arlington, Va.

Richard H. Ebright, a biochemist at Rutgers University in New Jersey, has followed the case closely and says it has been plagued by inexcusable delays and a reliance on dubious methods.

"The investigation appears to have had a very slow start and appeared for a long time to be off-track," he says. "The investigators did not make use of the scientific resources available."

For example, by accessing research databases, the investigators should have been able to identify in a matter of minutes most of the institutions that had used the Ames strain of anthrax that was used in the attacks, Ebright says. Yet subpoenas for samples of Ames anthrax weren't sent until February - and then their receipt was delayed further while a storage room was prepared at the Army's biodefense center at Fort Detrick in Frederick.

"They could have collected samples in days or weeks instead of six to eight months," he says.

Similarly, not until August did investigators find a contaminated mailbox in the Princeton, N.J., business district, after testing 600 mailboxes along the postal route where the anthrax letters were most likely to have been mailed. Ebright says that by his rough calculation, three technicians should have been able to test 600 mailboxes in about two weeks, leaving open the question of why it took 10 months. "It's incomprehensible," he says.

Steven M. Block, a Stanford University biophysicist, points out that investigators just returned to Florida last month to further trace anthrax spores in the tabloid newspaper building where the first person to die of inhalation anthrax, photo editor Robert Stevens, worked. The building had been sealed off since November.

"That could have been done six months ago," Block says. "They look more like Keystone Kops with every tick of the clock."

The lack of expertise with anthrax hampered investigators, who often had to make up their techniques as they went along. Certain angles that looked promising - such as genetic fingerprinting to trace the mailed anthrax back to a particular lab - turned out to be dead ends. But inexplicably, agents took months to speak with any of the two dozen living U.S. scientists who made anthrax in the nation's old biological weapons program, and some have not been interviewed to this day.