Suspect it is something to do with the detective's husband and son. Although I did wonder half-way through the episode last week if Billy's dad can be 100% ruled out? Could he be part of a cover-up act?
Thought it was good for the most part.
Didn't think the family mourning scenes were captured that fantastically. Can't imagine they are easy to though. Also felt it was a little bit 'jumpy' too often from one moment in time to another, which meant it lost a bit of fluency and therefore certain...