Rieli Franciscato, a government official and leading expert on isolated Amazon tribes,  in the forest near the Uru Eu Wau Wau reservation in the state of Rondonia, Brazil in  April 2019. Mr Franciscato was killed on Thursday. Photograph: Alberto Veiga/Reuters

A top expert on isolated Amazon tribes in Brazil was killed by an arrow that struck him in the chest as he approached an indigenous group, friends an(...)