Photo: A letter tainted with anthrax and sent to Sen. Tom Daschle in 2001 is examined. / FBI.

At a time when Americans' were on high alert after the Sept 11, 2001 attacks on the World Trade Center, they were confronted with a new fear: In October of that year, anthrax spores contained in letters, began arriving in mailboxes of celebrities and elected officials. Among those receiving the letters were broadcaster Tom Brokaw and Senator Tom Daschle. Five people died, 17 were sickened and the mystery of who could have done it remained. Until today, that is.

Answers to questions regarding the attacks that unnerved the country little more than a month after 9/11 are expected to emerge now that court documents relating to the case have been opened. The New York Times reported U.S. District Judge Royce C. Lamberth unsealed documents at noon EDT yesterday.

The documents relate to the investigation of an Army scientist, Bruce E. Ivins, who was initially believed to be assisting authorities to find the source of the attacks, but later became a prime suspect in the case. The anthrax spores were traced to his office. Ivins committed suicide on 29 July as authorities prepared to arrest him.

Part of the intense interest in this case stems from the ways researchers were forced to advance the science of genetics to eventually link Ivins to the specific strains of anthrax used in the attacks.

A senior FBI official involved in the case told the Washington Post that researchers made considerable advances in genetics. In fact, this investigation saw the development of a whole new science called microbial forensics.

Investigators used advances in genetic sequencing as well as controversial autopsies of the victims to identify the strain as one cultivated in Ames, Iowa, from a dead cow in Texas. Using analysis of the sample, scientists were able to conclude the anthrax in the letters possessed a flipped DNA sequence, which provided the scientific fingerprint which led to the United States Army Medical Research Institute for Infectious Diseases at Fort Detrick in Maryland where Ivins worked preparing vaccines against exposure to the bacteria.