I would be very surprised if it was Nifong - I would not for a moment be surprised, however, if it was one of his conspicuosly-absent-from-this-case bosses.... like a Police Chief or Mayor....
I agree.
Whoever the 'explosive DNA' belongs to, it will not likely ever be identified in this case as anything more than 'unidentified male'. It's not like all those likely suspects mentioned on this thread have their DNA profiles on file somewhere for ready reference.
All in all, it seems more and more likely to me, at least, that this case will just be dismissed sometime between now and the May hearing--probably just a week or so before the hearing is set to begin.