According to information released within the past week, some new, more detailed DNA analysis techniques have become available and affordable over the past year, and these have been used to "fingerprint" the DNA that caused the deaths and show they match the DNA used in Bruce Ivin's lab at Ft. Detrick.
While the details have not yet been released, I suspect the analysis looked for random mutations in the "junk" part of the anthrax DNA. Even assuming all the anthrax labs at Ft. Detrick started with the same exact Ames strain of anthrax, if each lab reproduced the anthrax independently, they would each end up with slight random differences that did not affect the function of the anthrax.
This case is applicable to our recent discussion of DNA "memory." You might say the DNA samples from the victims "remembered" the random mutations that occurred to their ancestors in Ivin's lab.
If you do not accept my use of the word "memory" in the Ivin's case, let me posit an analogous situation. Say a parrot has been stolen and is later recovered. The parrot is OK but, during its captivity it has added a few words to its vocabulary, and they are Hungarian words! The evidence of the parrot's memory of the Hungarian words would point to someone who speaks Hungarian as a likely suspect!
While discussing the Ivin's case with my wife, Vi, yesterday, she suggested that highly secure bio labs should consider purposely introducing telltale mutations in the junk DNA of the bioweapons in each lab. That way, if any of it was lost or stolen and used in a crime, the specific lab would be known and that could aid the investigation.
I believe there is a federal requirement that each batch of dynamite have a different mix of telltale materials added to it that are recoverable even after the dynamite has exploded. Anyone who makes a purchase must be identified and associated with the batch number of the dynamite. That way, when there is a criminal explosion involving dynamite, authorities can rapidly get a list of suspects - all those who have purchased sticks from that lot and others who are asociated with them or who may have stolen the dynamite from the legal purchaser.