Army scientist Bruce Ivins might not be the right suspect in the 2001 anthrax attack, which killed five people after anthrax was mailed to media organizations and politicians in the US not long after the September 11 attacks on the Twin Towers.

Security measures which were taken following the 2001 anthrax attacks crippled the national mail service and provisionally shut down a Senate building. In addition to the five deaths, more than 20 other people were sickened.

Ivins committed suicide last month by taking a massive dose of Tylenol mixed with codeine.

FBI investigators were very sure that Ivins was the person they were looking for. US attorney Jeff Taylor was very convincing at a news conference last week when talking about the case.

"He had the hours in the hot seat during the relevant times. We looked at the records when he was at work and when he would have had time to drive to Princeton, N.J. And it's clear from those records that he had time on the relevant occasions to drive to Princeton, mail the envelopes, and come back. It's a chain of evidentiary items that, assembled together, leads to one reasonable conclusion, and that is Dr. Ivins mailed that anthrax in those envelopes from that mailbox in Princeton,” Taylor said at the news conference.

However, new evidence on the case casts doubt on whether Ivins was involved in the anthrax attacks or not. An analysis on a hair sample recovered from a mailbox in Princeton made by FBI experts themselves and the US Postal Service inspectors revealed that the hair doesn’t match the lead prime suspect. Given the circumstances, there are many questioning the FBI investigation.

"I think it's going to be one of the great conspiracy theories, like whether we landed on the moon or whether Lee Harvey Oswald acted alone" in assassinating President Kennedy, Edward Lake, a computer specialist from Wisconsin whose Web Site has kept people in touch with the anthrax attacks for years.