You're welcome. The wannabe Oswald legal defense team will object to those two fragments from being admitted into court as evidence.
That is one of the reasons I found it strange that the Secret Service agents would allow a Navy NCO to assist in recovering evidence. If the fragment was found by someone other than a law enforcement officer, that could have tainted the discovery since they didn't have complete control of the limo during the search. Those are the kind of technicalities that arouse out of rulings by the Warren Court later in the decade so it's understandable why the Secret Service would not have been too uptight about having a Navy man assist in the search at the time.
I can picture Mills and Martinell showing up to collect the bone fragments that had already been found and the Secret Service was still going over the limo with a fine tooth comb. Maybe they just said, "Do you guys need any help looking for stuff" and the Secret Service saying, "Sure, why not".