How did the nurse get upset?
The police had made 2 arrests of persons they later had to release at that point, so I guess they didn't like to take any chanses with the third.
It should be said that the general opinion outside of medical reserarch was supportive of the police.
She hated that they had made her into a liar.
The registry is an enourmously valuble asset for the medical community but parents have to consent to the blood sample, so the police getting access was problematic to say the least.