I bet that Chandler PD is taking it seriously now that the FBI is involved.
I think they are doing their best to CYA to make it look like they were doing what they should have done in the first place.
My gut feeling is that they treated this case half-a**ed, and believed Alex when he said it was self-defense/ So, they dropped the ball, cut corners and just wanted the case closed and gone.
Something, someone else I was talking to pointed out the other day, was why they had a pool party later that day. The reason is that if the police came back to the house to further investigate, the house has now been contaminated with all of these other people's fingerprints, and DNA. LVD and Alex were literally covering up potential evidence, by contaminating the scene of the crime.
MOO