The FBI used an “information-technology” operation to arrest the husband and wife suspected of being responsible for the anthrax attacks in the US, according to documents released Monday.
The documents show how agents infiltrated the FBI’s computer network in the days before the attacks and searched through emails and other data before discovering the husband’s home address.
The FBI has denied it used the technology to target the couple.
The documents released by the FBI on Monday shed new light on the FBI probe into the anthracene attacks that killed 13 people in the United States on July 17, 2001.
They shed new doubt on whether the bureau had enough evidence to prosecute the couple or whether the couple were simply careless.
In one letter to a senior FBI agent, an FBI agent said he had used a software tool to scan a list of suspected FBI agents for possible anthrax.
The agent said the tool “looked like the ‘flesh-eating bacteria’ you are referring to” in a statement provided to the FBI by the bureau.
“The agent did not identify the software used,” FBI spokesman Matt Apuzzo said in a response to a query about the tool.
“However, the agent identified that the software was not used in any way to identify agents that were known to be involved in the anthrosis attacks, and that the agent did NOT use this software to identify known agents who were involved in anthrax or to investigate suspected anthrax.”
The agent said in the letter that he did not know the names of any of the FBI agents who had been suspected of anthrax in the previous days.
“I do not know why this software was used,” the agent wrote.
The letter was part of a series of letters sent by FBI agents to senior FBI officials over the next two months.
Apuzzos said the FBI had no knowledge of the tool used by the agent.
The agency declined to release the names or other identifying information of the agents who sent the letters.
Apuzzo also declined to provide any other details about the use of the technology, including whether it was used to identify suspected agents who might have been involved in attacks on the US.
The letter said the agent was not aware of any investigation into any of those agents, who were not charged with any crimes.
The FBI’s use of this technology to search the FBI network began on July 20, 2001, but the agency has said it did not have enough evidence.
The anthrax threat that killed the 13 people on the night of July 17 prompted the FBI to launch a “full and rapid investigation” into possible terrorist links in the attacks.
According to the documents released on Monday, FBI agents searched for the home addresses of at least three other FBI employees in New Jersey, Virginia and Texas.
A second letter from an FBI supervisor to Apuzzis said the bureau was conducting “a comprehensive review of its own computer systems” and that it had found “no evidence” that a specific person was linked to the anthranes.