A leading counter-terrorism investigator says white supremacists pose the greatest terror threat in the world today.
Former FBI agent Ali Soufan investigated Al Qaeda attacks including the 2000 bombing of the USS Cole and 9/11.
And like Islamic groups, he says the far right has constructed an international network with foreign fighters travelling to conflict zones like Ukraine to fight and become radicalized.
The alleged Christchurch gunman says he went to Ukraine, a claim that is currently unverified.
As Mike Wesley-Smith reports its just one of many possible lines of inquiries for New Zealand authorities as they scramble to determine whether our darkest day was one we should have seen coming.