Behind scrub on a nondescript South Australian highway lay a battered suitcase. It had been abandoned and largely forgotten, yet its presence was incongruous in this vast, unforgiving landscape. Last month, one passer-by was so disturbed by what he found after peering inside that he contacted police. Just off the Karoonda Highway in Wynarka, in South Australia's Murray Mallee region, a terrible secret had lain in wait.