burn in his memory throughout the investigation. >> the first thing that immediately hit me was the dora the explorer pillow. and it had blood on it. >> what was the emotion when you saw that? >> anger. >> with two young kids of his own, this case had already hit rick arnold hard. on the spot, he made a promise to erica's grandmother. you said, we're going to find who did this? >> yes. >> that's a lot to promise somebody, isn't it? >> yes, it is. >> coming up, a glimmer of hope from baby erica. >> i was rubbing her hand and she opened her eyes. >> when "dateline" continues. so you can spray and stay. febreze one.