>> what was he doing when officers were not watching him? >> he sat in this manner. >> sleeping at moments. >> reporter: and sipping his signature drink, dr. pepper. >> reporter: free on bail, lars understood he was still under the microscope. >> it was difficult. >> he didn't sleep much. >> reporter: watching lars suffer was torture for ken and kristi. they knew how much their brother loved debbie and how dark and confusing that house could be at night. >> you felt it was important that we come to the house now. >> yes, i did. >> why? >> because no one realizes how dark it was. >> we're here. it's around 4:00 in the morning. >> yes, it is. >> reporter: this was lars and debbie's bedroom. >> the bed was on this wall. >> reporter: ken itzo walked us through the story lars told him countless times -- >> he wasn't sure what he was seeing. he just thought it was an intruder, maybe two. >> there's the thought of, well, debbie's only 5'3", she's blonde. she was wearing a light t-shirt. how could he not see his own wife? >> at 4:00 in the morning. you don't see anything. it's dark. and i don't think size, weight, or complexion matters at 4:00 in the morning, when you're