really, really good piece of physical evidence. >> reporter: what you found so far wasn't it. >> no. >> reporter: okay. so specifically what did you find of probative value? >> i didn't find anything. we took his cell phones. there were two cell phones in the car. >> reporter: but basically nothing. >> no. >> reporter: detective ruiz was assigned to the dining room, which clearly doubled as an office. what did you see? >> i saw a lot of paperwork. there was lots of paperwork. files everywhere on the table. >> reporter: room was full of paper. >> yes. >> reporter: the sun was just breaking over the horizon. long rays of morning light angled through the blinds. detective ruiz was poking through all those papers and office supplies. when a curious thing caught his eye. it was the way that almost horizontal beam of light glanced off a blank sheet of paper. >> i noticed that the white sheet of paper had several impressions on it. >> reporter: impressions? >> yes. >> reporter: you mean writing on it? >> yes. like when you draw something on a top sheet of paper and it goes