New Zealand is in shock and mourning after the worst attack in its history.
49 worshippers in two mosques were shot dead while saying Friday prayers.
Police in Christchurch arrested Brenton Tarrant.
He's appeared in court charged with murder.
After the attack was live-streamed on Facebook, detectives are focusing on the perpetrator's online activities and a so-called 'manifesto' full of far-right, ultranationalist and anti-muslim views.
So what should be done to stop hate speech online?
Presenter: Adrian Finighan
Guests:
Tahir Nawaz - President, International Muslim Association of New Zealand
Raphael Bossong - Research Associate, German Institute for International and Security Affairs
Nolen Gertz - Technology ethics expert
