We don't know how the blood got in the garage. We don't know for sure about the dismemberment but let's say the blood is from that process only. They thought they could do that cleanly in her garage. Stuff the pieces in bags and drive away. Drop the bags in Hartford and they're done. Simple as that. Only, they didn't count on some of the blood splattering and being detected and, inexplicably, they didn't figure out that the cops could track his cell phone after the fact. At least, that's what I figured happened. Hope they will find out soon.