Anthrax-free Senate building reopens

The final cost of the clean-up may be more than $14m

A Senate office building has reopened in Washington after a three-month shutdown to rid it of anthrax contamination.

The Hart Building is home to half of the 100 senators. It was closed in mid-October after a letter addressed to Senate majority leader Tom Daschle was found to contain highly toxic anthrax spores in powder form.

Biohazard workers toiled for months to disinfect the Capitol

The letter was one of a number of such deliveries to government officials and media companies in Washington, Florida and New York.

During the scare, five people died and several others were treated for anthrax poisoning.

Coming just after the 11 September suicide attacks, American officials originally suspected a foreign source, but investigators now believe the anthrax attacks had a domestic origin.

US scientists say they have found tiny differences among the anthrax samples that may help investigators to trace the source.

Lost specimens

Scientists at the Institute for Genomic Research in Rockville, Maryland, say they have pinpointed a few subtle genetic variations between two anthrax samples they are comparing: anthrax used in the Florida attack and anthrax held by a UK biological weapons laboratory that originally received its sample from the US Army lab at Fort Detrick, Maryland.

No motive has been found for the anthrax attack on Senator Daschle

Researchers are now verifying the differences, which may lead to a breakthrough - although some experts voiced scepticism.

Earlier, an inquiry into allegations of lax security at the Maryland research centre found evidence that more than two dozen potentially dangerous samples had been missing.

The lost specimens included the microbe that causes anthrax and the ebola virus.

Investigators said that unauthorised anthrax research was taking place at weekends and evenings in February 1992.

The discoveries, which have only now come to light, were made by army investigators 10 years ago.

Analysts say these revelations add weight to an increasingly popular theory - that last year's attacks were carried out by a current or former scientist at the Maryland centre.

No progress

The Federal Bureau of Investigations has made little progress in tracing the source of the anthrax-tainted letters and is set to offer a new $2.5m reward - double the existing reward.

More than 5,000 environmental samples were taken during the clean-up of the Hart Building, which involved fumigation with a powerful gas, hi-tech vacuums, foam and liquid cleansers.

Twenty-eight congressional employees were exposed to the bacteria in the letter postmarked Trenton, New Jersey, but officials say none of them contracted the disease.

"I feel completely safe," Senator Daschle said on Tuesday, returning to the building. "It's good to be back."