WASHINGTON  The Federal Bureau of Investigation on Wednesday outlined a pattern of bizarre and deceptive conduct by Bruce E. Ivins, an Army microbiologist who killed himself last week, presenting a sweeping but circumstantial case that he was solely responsible for mailing the deadly anthrax letters that killed five people in 2001.

After nearly seven years of a troubled investigation, officials of the F.B.I. and the Justice Department declared that the case had been solved. Jeffrey A. Taylor, the United States attorney for the District of Columbia, said the authorities believed “that based on the evidence we had collected, we could prove his guilt to a jury beyond a reasonable doubt.”

Some survivors of the attacks and members of Congress said they were persuaded by the evidence against Dr. Ivins, laid out in hundreds of pages of applications for search warrants unsealed for the first time. But some independent scientists, friends and colleagues of Dr. Ivins remained skeptical, noting that officials admitted that more than 100 people had access to the supply of anthrax that matched the powder in the letters.

Lawyers for Dr. Ivins reasserted their late client’s innocence and criticized the government for presenting what they called “heaps of innuendo” that failed to link him directly to the crime and would never have to be tested in court. “It was an explanation of why Bruce Ivins was a suspect,” said Paul F. Kemp, who represented the scientist for more than a year before his death on July 29 at age 62. “But there’s a total absence of proof that he committed this crime.”