Princeton, N.J. ? A day after the announcement that a New Jersey mailbox tested positive for anthrax exposure, federal agents canvassed the streets with a photograph of the researcher under scrutiny in last fall’s anthrax attacks.

A senior U.S. law enforcement official on Wednesday confirmed that FBI officers are showing Steven J. Hatfill’s photograph to business owners in the area.

The agents are trying to determine whether anyone saw the 48-year-old former Army biological weapons researcher near the mailbox last September or October when the anthrax-laced letters were mailed, the official said, speaking on condition of anonymity.

An FBI official would not say what, if anything, authorities had learned from people who saw the photo.

Ross N.A. Woolley, an architect with Woolley & Morris in Princeton, said investigators had showed him a picture of Hatfill much like a photograph widely shown in the media.

“I immediately recognized it,” Woolley said Wednesday.

Hatfill, a 48-year-old former Army biological weapons researcher, has denied any role in the anthrax-by-mail attacks and has criticized the FBI and media for engaging in what he described as personally damaging speculation and innuendo.

After news of the mailbox finding surfaced, Hatfill advised his attorneys that he had never been in Princeton, N.J., said his lawyer, Victor M. Glasberg.

The FBI says Hatfill is not considered a suspect, but it also says he is one of about 30 “persons of interest” in the case.

Several Princeton merchants told The Associated Press that agents had spent two days circulating the picture and asking employees if they recall seeing the man in the area last September and October the height of the anthrax attacks. They said the agents didn’t reveal the man’s identity.