A case like this is necessarily going to be circumstantial. Good circumstantial evidence, however, is proof of circumstances that exclude any logical explanation except a defendant’s guilt, OJ’s DNA and its locations that proved he murdered Nicole being good examples. Thusfar, however, the FBI has merely been leaking a lot of virulent smears about Ivins, smears that probably wouldn’t be admissible in court. That smearathon, all by itself, gives me serious doubts about the FBI’s case. It sounds altogether too much like the Haditha Marine and Duke Lacrosse Players smearathons.
Before he slipped into his current state of dementia, Vincent Bugliosi provided one of the best analogies for circumstantial evidence in his book, "Outrage" which discussed the Simpson case. Bugliosi wrote that the Simpson defense painted all the circumstantial evidence as a chain, and once one link was broken the entire chain would give way and fail. Bugliosi stated that it should be more properly viewed as a rope with numerous strands. One individual strand may be broken, but depending on the strength and number of other strands, may make little to no difference at all.