The guy visited many countries in Europe and Asia. They say travelling the world and seeing so many cultures opens peoples minds but clearly not this guy. The bizzare thing is he had very positive things to say about Pakistan.
My feeling is and I know this is really wild speculation that he already had unstable mind that was influenced by racism which is endemic in Australia. His visits to Balkans in particular Bulgaria and Turkey exposed him to the historical rivalry between Christians and Turkish Muslims. He went on about Istanbul [Constantinople] returning to Europeans and the Turks restricting themselves to east of the Bosphorus or hell would visit the Turks.
Thus it is reasonable to assume from his 'radical footprint' that he was radcalized by far right Balkan groups as can be seen from the referances he makes. The worse people here are the Serbs who were behind the genocide of Muslims in Bosnia in 1990s.
TRT reported that he might even have been planning a attack in Istanbul.
@KediKesenFare @T-123456