I thought it was standard procedure to fingerprint someone upon their arrest. Maybe they've fingerprinted him by now, and just haven't updated the record.
His old apartment would require some major work to make it habitable for a normal person (anyone with a working olfactory sense). I would feel sorry for his aunt, but she seems to have been his chief enabler and shielded him from the consequences of his actions for a long time, so she gets no sympathy from me. I don't have any sympathy for his mother either, she could have gotten Nick help ages ago and possibly have prevented this. I hope Amber's dad takes her far, far away from her and gets her the help she desperately needs to grow into a stable adult.