I know it's a common trope in murder mysteries with plucky amateur detectives that the police in general suck at their jobs, excepting maybe one particular cop, but damn, didn't anybody notice two left shoulders in the incinerator ashes?! I don't work in forensics, but I feel like it's pretty basic to measure how much ash was in there and if all the parts go together lol. Does Detective Williams have to do fucking everything over there?! Jesus! When she went on maternity leave the criminals of NYC must have been thrilled.
This is not the first time weird stuff has happened at the precinct, somebody messed with the Tim Kono evidence too. Detective Donna Williams sent evidence to the lab and it was never actually sent or something like that. She said that meant someone higher up wanted the case gone, or quiet, something like that, I'll have to rewatch the scene. At any rate, something weird is happening over there, and I bet eventually, possibly this season, there's going to be a murderer based over there. It's too weird, not just the typical "incompetent police" trope to facilitate the storyline.