In releasing a 92-page report on Friday, the US Federal Bureau of Investigation closed its investigation into the 2001 anthrax case, reports the New York Times. The FBI concludes that the attacks were carried out by Army biodefense researcher Bruce Ivins, who killed himself in 2008. The bureau theorizes that the notes included with the anthrax mailings contained coded messages based on DNA biochemistry. At Adaptive Complexity, Michael White discusses a letter sent to the New York Post in which As and Ts were bolded, giving TTTAATTAT. Breaking that down by codon, it becomes TTT, or phenylalanine (F), AAT, or asparagine (A), and TAT, or tyrosine. The FBI report says that from this “two possible messages emerged: (1) FNY — a verbal assault on New York, and (2) PAT — the nickname of former colleague #2.” The report also includes a recorded conversation between Ivins and a friend : “If I found out I was involved in some way...” Ivins says. “I do not have any recollection of ever doing anything like that,” he says, adding, “I can tell you, I am not a killer at heart.”