The former headquarters of a supermarket tabloid was declared clean of anthrax spores Monday, almost three years after it became the first target in a series of deadly attacks.

The cleanup crew finished decontaminating the American Media Inc. building at 7:30 a.m., said Karen Cavanagh, chief operating officer of BioONE (search) and Sabre Technical Services.

"We have no viable spores in the building," Cavanagh said.

Officials started pumping chlorine dioxide into the building Sunday. Follow-up tests are required before a quarantine is lifted, which could take up to eight weeks.

The arrival of anthrax in the mail at the building was the first in a series of still-unsolved attacks that killed five people, among them photo editor Bob Stevens of AMI's tabloid the Sun. The attacks rattled a nation shaken by the Sept. 11, 2001, terrorist attacks a month earlier.

AMI, which also publishes The National Enquirer (search), abandoned the three-story office after anthrax was found in 2001. A real estate investor bought the building for a paltry $40,000 and made plans to lease it to BioONE, a company established by former New York City Mayor Rudolph Giuliani (search).

BioONE plans to occupy the space by the end of the year as the headquarters for its new crisis management venture.