I'll let Denny give you a more definitive answer on this. I'll simply say that it appears that you're looking for the Holy Grail; "The" answer.
Ask yourself this:
If Fackler's info is not enough; If the FBI tests are not enough.....what is it that you think we could provide that will be authoritatively different? Basically, anyone who tries to report on such issues, absent enormous resources to do it right, is simply performing "Junk Science". I don't like Junk Science.