. >> so detective schartner made patricia a promise. >> we were sitting in the car and i remembered justg and crying and crying. and then he promised me, he said i'm gonna get him. he said if it's the last thing i do. he said i'm gonna get him. >> to do that, detective shot near and nelson had to confront a terrifying question. >> you've got two murdered mother daughters within, across the fence, virtually. >> right. >> same neighborhood. so you're thinking are these things related? right? >> you'd have to think that if they are related, you have a serial murderer on your hands and you don't know when he's going to hit next. and you don't know who he's going to hit next. >> coming up. >> a neighborhood on edge. police under pressure, and the question everyone feared, would there be another victim? >> it was wide open. we had nothing. that's when it gets scary. >> when dateline continues. you can't leave without cuddles. but, you also can't leave covered in hair. with bounce pet, you can cuddle and brush that hair off. bounce. it's the sheet. your best defense against erosion and cavities