Mark Erin Rust

S1, E5: Step-by-step, Mark Erin Rust escalated to become a killer. Starting out as a sex pest, he grotesquely graduated to rape before randomly murdering complete innocents. All the time he was suffering from a little-known syndrome called 'Klinefelter's' which restricted the growth of his genitalia. Adelaide was a dangerous place to be for the years he prowled the streets.