A new investigation into the Christchurch Mosque shooting delves into the shooter's motivations - and questions whether he should be identified as a 'lone wolf'.

In the six-part podcast, Secrets We Keep: Lone Actor, investigative journalist Joey Watson traces the killer's descent into extremism and wonders if he truly acted alone after being radicalised by online communities.

Watson explained that he went through the online communities that radicalised the shooter and saw how he was desensitised to violent acts.

"The closer I looked at it, the more I came to see that based on how these ecosystems operated before the attack, what happened in Christchurch - it certainly wasn't inevitable, but it's tragically explainable."

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