I thought when he was vulnerable he was "human". If they aren't looking for alien DNA would they notice his blood wasn't human?
Beats me. I am not sure how different his blood is from human blood. He was definately normal enough to not be detected by that police in ASU, but they seem to have only had a psychiatriast look at him and not do any blood tests.
I think how human-like his blood is is a question you can answer in any way you chose. And I don;t think we will be able to cite anything from the show to the contrary.
