they used science to carbon-date the bones and now claim as follows:
Found: bones of John the Baptist June 15 2012 at 09:14am By Daily MailLondon - When archaeologists claimed to have found the bones of John the Baptist, experts were sceptical.
But carbon dating tests carried out at Oxford University have provided scientific evidence to support the extraordinary claim.
A knucklebone taken from the remains – which include a skull, bones from a jaw and an arm, and a tooth – has been dated to around the 1st century AD, when John is believed to have lived. The fragments were found two years ago in a stone box in a ruined Bulgarian monastery.
Oxford professor Thomas Higham said: “We were surprised when the radiocarbon dating produced this very early age. We had suspected that the bones may have been more recent than this, perhaps from the third or fourth centuries.” - Daily Mail
I suppose John was the only person alive at that period though, it would simply be inconceivable to claim the bones could belong to a peasant…