Yeah. The "found later" thing has been kicking around in my head. If I recall correctly, found later and they were surprised to find it.
Let me begin by saying, everyone is having a difficult time reconciling this evidence with reality. Well, except Spivey who believes it indicates a sexual motive behind the crime. He has more evidence than me, to be sure, but it kind of looks like a crime without a clear motive.
However, the DNA so far matches no one. So, either we have a unique type of sexual predator who has no DNA on file to match (for whatever reason, never left additional DNA or never reoffended or whatever).
Or we have a consensual sexual encounter that occurred somehow in this very crowded night, and somehow no one has ever figured out who on earth it could be. I really think this gets proposed just to account for the problems with the DNA. It's not impossible, but given most known scenarios have J.B. and Tracie just driving around Alabama ... More farfetched than it seems like it would be.
Think of the other clues that were difficult to reconcile like the driver's license (proves to be a non issue) and the "getting lost in Ozark while trying to get to Headland" (proves to be triple plus wrong); I can't help questioning the veracity and origin of it.
But, say it is there, I am wondering about cross contamination during examination. The shell casing was sent to the wrong place and poofed out of existence. The car was released to the insurance company when that wasn't supposed to happen. So, that's how things were handled.
Then there's the fact something could have happened in between removal from the crime scene and the surprise discovery. Sadly, sadly, things like that do happen. And it would explain why nothing matches it.