From other crime stories, we know that often they like to use bleach to clean it up. Bleach has a strong odor that doesn’t go away quickly, and it discolors things like carpets and wood floors (furniture, etc. also). I would think the house would have fairly REEKED of bleach for some time—and the wife, of all people, would have not only noticed it but also should have been able to figure out what it had been used for.
As to why/how she might have been killed in the garage, yet blood in the living room—maybe it started in the livingroom, and she tried to get away from them—they caught her, dragged her into the garage, then hit her with the crowbar? Just brainstorming, please don’e assume I think that IS what happened, but it seems to be one possibility.
http://edition.cnn.com/2008/CRIME/01/11/missing.marine/?iref=mpstoryview
Tests found the “trace of violent activity in the house” and “evidence of an attempted cleanup,” said Onslow County Sheriff Ed Brown.
OR Maria was talking to Christina in the living room when Cesar came in from the garage with a crowbar behind her.
I am off to have lunch at the O-club. Be back later :)