mrs. carrick had come in the store and she, she kind of turned her back to him when he approached her to say hello and that was the last time she ever spoke to him. >> reporter: but for mario, life was moving on. >> here he is receiving his degree in finance from illinois state university. three years after brian's disappearance. >> hey! >> reporter: mario joined the family grocery. worked as a manager and helped build the business. >> that was not the only store that he was going to have. it was always going to be two stores and three stores and four stores. >> reporter: that grand plan would never happen. mario's world was about to collapse around him. a break in the case. this stockboy, shane lamb, would change everything with a sale of violence in the produce cooler the night brian vanished. >> i hit brian two times. bleeding from his mouth. i thought i knocked him out. >> where's mario when you're doing this? >> right in the doorway. >> reporter: what did happen to brian carrick? stay with us. what did happen to brian care rik. stay with us. mmmm... when you add liquid gold velveeta to