>> this is detective rick arnold. today's day is may 18th, 2006. >> reporter: a video camera rolled as detective arnold processed the crime scene honing in on clues. >> this drew the victim's body, the shell casing. >> reporter: the hard reality of death lay alside-by-side with t everyday images of young life. aaron's body in a pool of blood near af red kitty wagon, a she casing in front of a box of diapers, and the bed where erika once jumped for joy was now covered in her own blood. >> the blood on the sheets. the pillow and pillowcases. >> reporter: detective arnold noticed r something on the bed that wouldon burn through his memory throughout theur investigation. >> the first thing that immediately meet was the dora explorer pillow and it will blood on it. >> reporter: what was the w emotion when you saw that?