rookie cop knew she'd have to learn about the victim. and so she began with something easy. she found david jackson's mother, judy carlson. she found judy's son, actually, who called his mom. >> and he said, are you sitting? and i said, yes, and they said, they reopened david's case. >> the detective and the mother talked about david for hours. it wasn't a problem for judy, she loves talking about her boy, even now, to us. >> david was my first child. he was just -- loved everything and everyone. ♪ happy birthday to you >> david jackson was the eldest of judy's three children. and mark jackson idolized his older brother. >> he looked out for me. he was that way with his friends, with everybody. >> bill brown was one of those friends.