In regards to so many saying the search at AG house last night confirms he is/they are suspects, surely for the sake of a future trial of anyone else, LE would want to be able to say, "We searched the SIL's house repeatedly, luminoled it, processed their vehicles, etc. and found absolutely no evidence they were involved. And we have pictures of the luminol tests to prove there's no blood there!" At this point, if SIL hasn't been arrested after all that scrutiny, it makes me think he's less likely to have been involved rather than more.