Potentially unpopular hypothesis, but it is possible that no unknown DNA was found in the home and that law enforcement seeded that information to media outlets in order to stoke paranoia and an irrational response. Because paranoia certainly breeds irrational responses, and I imagine gets more criminals caught than DNA does.
It seems far more likely to me that if law enforcement found unknown DNA in or around the home that that isn't something they would want to disclose to anyone publicly. We know from reporting that they have digital sweepers on land and in the air, and are fiendishly monitoring cell and internet communications (think NSA) for a digital fingerprint, so I imagine they'd love a login or cell call to track right about now.
JMO.