For whatever reason the writers have decided to write Chase as blindly on a quest where the mission is already done. ASL BLQ stated, it all made sense when Willow was on trial because he was fighting to clear her name. She was acquitted and has been reunited with her children so he has ample reason to lay down his sword. Dante already said the handling of the keys has all but assured Michael cannot be charged without the PCPD looking culpable. But we are to believe that Chase isn’t cognizant of ANY of this? It’s absurd.
Chase is a seasoned veteran and knows all to well about chain of custody and how it would impact the case. As Ladfan mentioned, this would all make sense if Willow were actively manipulating him and she isn’t. It’s just a dumb plot point showing an otherwise, boyscout with an identity crisis. Heck, if/when he’s fired maybe Jack will hire Chase at the WSB! 😃