karen foster: i only got to see her face. it's just incredibly sad. and you think, oh my god, it is her. and you can't believe that your baby is lying there, cold and lifeless. keith morrison: the next day, karen saw her baby again, saw more than her face, and noticed something that seemed to confirm what she already believed. it wasn't a hiking accident. she called the alaska state troopers. her knuckles were broken. so i'm on the phone screaming to them, saying, no, you've got to get back. you got to take more pictures. these are defensive wounds. keith morrison: look again at bonnie's body, she demanded. look harder. what happened to bonnie craig that september day, screamed karen, was murder. craig melvin: coming up. i think my mom felt very responsible. like i caused this. i caused this, you know? they killed bonnie because of something i did it. craig melvin: was her child's death revenge? when dateline continues. swiffer duster traps 4x more dust, for a clean even mom approves of. that reach! making hard to reach... so easy. swiffer. wow. the m