The Back Pack Killer. Australia's worst solo serial killer, Ivan Milat, is now serving life for the murders of seven hitchhiking backpackers between 1989 and 1992.

Many questions remain unanswered and there is uncertainty about the full extent of Ivan Milat's crimes. Did he murder for entertainment? Some say his motivation lay in his family background and upbringing.

Ivan Milat grew up as one of 14 siblings, a close-knit family who didn't mix with others. They were surrounded by guns amidst an ethos of lawlessness and unbreakable family loyalty.

Did he kill alone? One of his siblings, Boris, broke the bonds of rigid family loyalty to speak out against the convicted killer. He said it is likely that there are more of his victims yet be found.