Anthrax detected in New Jersey post-box

Anthrax-laced letters were sent to Washington

US postal inspectors investigating the anthrax mailings linked to five deaths last autumn have found a post-box testing positive for traces of the bacteria.

The mailbox, found in Princeton, New Jersey, and has been sent to an army facility in Maryland for further tests, US Postal Service spokesman Dan Mihalko said on Monday.

Dr Hatfill says he is innocent

He said the mailbox was discovered during an investigation of hundreds of boxes from which mail is sent to a sorting centre in Trenton, New Jersey, where four anthrax-laced letters were postmarked last year.

The US authorities are eager to find any clues which might lead them to the person behind the anthrax attacks.

Over the weekend, one of the alleged suspects - biological weapons expert Steven Hatfill - insisted that he was not to blame.

Dr Hatfill has attracted attention because of a novel he wrote about a bioterrorist attack, but the authorities have found no concrete evidence linking him to the letters.

Deadly bacterium

Over 300 post-boxes have so far been tested, but the box found in a street adjoining the Princeton University campus is the only one to register positive for anthrax, said New Jersey Governor James E McGreevey.

Four anthrax-laced letters were postmarked Trenton, New Jersey

Postal officials say further testing is essential - field tests have been wrong in the past - and the box has been sent for forensic analysis.

Five people died and 13 fell ill last year when anthrax-tainted letters were sent to government officials and media outlets in Washington, Florida and New York shortly after the 11 September attacks.

Two Washington postal workers died of inhaled anthrax, as did two women thought to have been infected from the mail.

A Florida employee of a national tabloid newspaper also died of inhaled anthrax, and though no contaminated letter was found in connection with his death, investigators found traces of anthrax in the company's mailroom.

Investigation

The FBI launched an investigation into the anthrax attack in October, and the US authorities are offering a $2.5m reward for information leading to an arrest and conviction.

Scientists say they are not surprised that the case remains unsolved. It would be easy for a skilled microbiologist to have disposed of any evidence that remained, they say.

Even over-the-counter bleach will destroy any trace of anthrax, said Philip Hanna, a microbiologist at the University of Michigan Medical School.

"The chances of finding something get more and more remote," he said.