the caller was the knoefel 13-year-old daughter meghan.er meghan was being brutally stabbed by before her eyes. >> they're stabbing my mom with a knife. >> who has a knife? >> i have a female yelling on, the phone someone has a knife. >> megan was yelling, screaming, telling someone to stop. you're hurting, why are you doing this. >> oh my god. >> in the background, lisa can be heard, pleading for help. >> call 9-1-1. >> what is going? on >> it's really chilling to listen to. >> take a deep breath. i can't understand you. >> first responding officer randy -- arrived at the knoefel home and found meghan frantic at the front door. >> she is waving her hands, you need to hurry, hurry. >> he learned that keven knoefel was away on business, leaving lisa, macon, haley, and their foster daughter sabrina home. >> worst-case scenario was going through my head, what am i going to see, how bad is this going to be. >> it was far worse than he could have imagined. out of the master bedroom, came the knoefel 18-year-old foster daughter sabrina, holding

. >> when she was told about being placed with the knoefel family, she was ecstatic. >> a happy home