Koh Tao, where Hannah Witheridge and David Miller were murdered, is steeped in paradoxes. Photograph: Alamy Six weeks on, there is little to mark the spot on the idyllic rocky beach inlet on Koh Tao where Hannah Witheridge and David Miller met such brutal deaths ; just two tiny piles of stones separated by a line of twigs in the sand, someone’s modest, anonymous, temporary memorial. A few hundred yards away along Sairee beach, the main tourist drag on the Thai holiday island, life continues as normal. Business, says a French man running a dive shop – much of Ko