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.... or college official who took another job in another state...
The only way that the DNA can be matched to a particular person is if that person's DNA profile is in the registry or they give a sample. The only way someone's DNA gets in the registry is through a criminal case against them. Unless the police chief and the mayor gave samples, which would be absurd since they aren't accused, it isn't them.
There has to be a nexus between the profiles found on her and a legally-obtained source against which it can be compared that the lab was asked to compare it with.