. >> reporter: first, michela. then, jenny. >> bloodhounds came, police were there. >> this is a little girl that was doing nothing more than riding her bicycle in a park. >> two young girls taken. >> the similarities. blondeme blonde, blue-eyed, riding a bike. >> somebody who is targeting little girls. >> exactly. as a little kid, it definitely scared the heck out of me. >> she was a girl then, too. solving these mysteries became her mission. >> so, how many names did you have? >> about 2,300 names. >> reporter: could cutting-edge technology crack an ice-cold case? >> i was like no way. >> i believe in the devil. and people that don't believe in the devil, i think they're in for a big surprise. >> hello and welcome to "dateline." michela and jenny were just like most kids their age. they loved riding bikes and playing outdoors. the fun-loving girls didn't know each other, but they would be forever connected through tragedy. decades later, a detective would leave no stone unturned on a quest for justice. and in the

. >> reporter: first, michela.unds came, police were there. >> this is a little girl that was doing nothing more than riding her bicycle in a park. >> two young girls taken. >> the similarities. blondeme blonde, blue-e