According to this article in the NY Times today, the evidence is circumstantial and does not definitiely identify Bruce Ivans as the sender of the anthrax threats. The dna tests suggest that the anthrax samples came from his lab but that at least 10 people had access to the samples.
Anthrax Evidence Called Mostly Circumstantial
According to this article in the Wall Street Journal, several experts don't even think that dna analysis tests can correctly identify the specific lab that that anthrax sampless came from.
wsj: Forensics Gave Investigators Little to Work With
"Genetic analysis of the spores showed that the anthrax was the Ames strain, but that was little help since many labs had that strain. Further research, involving committees of scientists from government and academia, focused on how quickly mutations would arise in Ames strains that were kept apart, such as in different labs. Radio-carbon dating was done to try to determine when the bacteria were cultured. Investigators examined each minute and obscure element mixed in with the anthrax: "We're looking at cations, anions; we're looking at inorganic matter; we're looking at sugars, whether augurs are present," said one senior investigator at the time. "We're doing high-resolution scanning electron microscopy and transmission-electron microscopy." These tests also added another major, time-consuming hurdle: validating them on practice material, so that the science could withstand a challenge in a court of law.
Anthrax extracted from victims matched the strain in Bruce Ivins's lab, according to a federal law-enforcement official.
But several scientists who have spent years analyzing the genetics of bacteria doubt any DNA fingerprint exists that could definitively isolate a particular lab.
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