Crime Beat S06E12 - A Million Dead Ends

On May 14, 1971, just after dinner, six-year-old Ljubica Topic wandered off while playing outside with her older brother and some friends. When her brother gets home, Ljubica isn't there. Questioned by his mother, he reveals that a stranger had approached them asking for help and Ljubica had gone off to assist. After a frantic search, the young girl is found dead just a kilometre away. Who did this and why did it remain a mystery for nearly 50 years?