You are right. I think the inconclusive DNA was on the fake finernail. I think that a towel found in his bathroom on the other side of the house had his DNA and someone elses unrelated to this case. Of course this is Nifong's weak attempt to change the story to make that towell evidence. The problem is where is Mangums DNA on it?
Another site had a link to the typewritten notes of the detective and now they say the rape happened in his bathroom...which happens to be where the all purpose towel was found.
I'm looking for the link.