Her DNA won't convict him..It did give them probable cause to arrest him, along with their other information..He seems to have been a collector of memorabilia from his victims..I wonder if they have discovered more..His DNA has been matched by now to evidence collected years ago.
BTK's hunger for recognition and desire to taunt the police again did him in. He started believing in his own invincibility.
At least he didn't kill again....at least not the we know of.