Sorry. I figured out what I was doing wrong.
I suspect the issue is that I put the game down for a minute during interrogating Brian Reid and might have failed to use one of the "Contradict" prompts.
I went to Pete Baxa's barbershop which is now closed and am unable to retrieve the bloody tissue with Pete Baxa's DNA.
Other forums suggested going to other locations and analyzing evidence until Pete Baxa returns to the barbershop. This did not work.
I tried to re-initiate the interrogation both by going to the interrogation room and by visiting Brass' office but this did not work either.
Is there something that I am overlooking? I hope I don't have to start this case all over from the beginning.