That i don't know. But he first started going to the National Archives in the mid-1990's and has been studying the documents ever since. He was friends with Pete Bagley (of the CIA Soviet Russia division around the time of Oswald) and got his insights on the whole assassination.
Here is what Vincent Drain, the FBI agent that the DPD trusted to take and return the items, had to say to Larry Sneed in an interview:
Earlier in the evening, about 8:00 o’clock, the division chief had talked to me on the telephone and informed me that the FBI in Washington demanded that we bring to them for examination the rifle, the revolver that was used to kill Tippit, as well as the different paraphernalia such as identification cards and other small items that Oswald had on him. I discussed it with the police chief and told him that we’d keep the chain of evidence intact and that I would pick them up there myself and wait for them until they were examined in Washington then bring them back. So it was turned over to us. By the time we got it all boxed up, it was near midnight. Meanwhile Washington was calling down about every fifteen minutes wanting to know where the material was. All of a sudden I learned that neither American nor Braniff had any flights to Washington out of Dallas after midnight. We were told that the FBI in Washington wanted the material by morning if we had to walk it up there. That’s being facetious, but . . .Now, I really don’t try to tell others who they should believe. But I do encourage others to ask themselves if they have a bias against the authorities. And in this case I encourage others to ask some simple questions about conspiracy theory authors like Blunt, similar to the ones that I asked and received zip for answers. It appears to me that none of Blunt’s allegations make any sense. You appear to have jumped to some conclusions regarding the FBI trying to hide some things.
If folks would just allow themselves to consider that it is possible that the authorities connected to this case were honestly doing their jobs as best as they knew how. And that it is possible that the conclusions that they came to are correct. Then approach the case with an open mind. Then the evidence speaks for itself.