At the time of the incident, the Auckland region was under strict alert level 4 lockdown due to an outbreak of the COVID-19 Delta variant in the city on 17 August 2021.

[17] The perpetrator was identified as Ahamed Aathill Mohamed Samsudeen[18] (1988/1989 – 3 September 2021) a 32-year-old[19] Sri Lankan Moor national who arrived in New Zealand in October 2011.

[21][22][23][24] Samsudeen sought refugee status as a Tamil Muslim, alleging that he and his father had issues with Sri Lankan authorities because of their political background.

[25] In 2013 the Immigration and Protection Tribunal said that Samsudeen was "persistently re-experiencing traumatic events"[26] and concluded he had a well-founded fear of facing harm if he returned to Sri Lanka.

[18] His claim to asylum was supported by scars on his body, as well as a psychologist's report which said Samsudeen presented as a "highly distressed and damaged young man" suffering from post-traumatic stress disorder and depression.

[22] On 23 March 2016, Samsudeen came to the attention of New Zealand police after posting photos of horrific acts of war brutality on his Facebook page, along with remarks praising the Islamic State terrorist strikes in Brussels the day prior,[18] hence being consider a supporter of ISIS.

[3] Samsudeen was deemed a public safety danger after purchasing large hunting knives on two occasions and owning Islamic State videos.

[27] He was charged with having these goods, and pled guilty to counts of intentionally distributing restricted publications, fraud, and failing to cooperate with authorities in the execution of their search warrants.

Another search turned up extremist content, including an Islamic State film showing a masked man slitting a prisoner's throat and wrists in order to kill a "non-believer".

[34] In July 2020, Samsudeen remained in custody awaiting trial, and the Crown attempted to add an additional charge for the knife and internet posts under the current Terrorism Suppression Act.

"[35] In May 2021, Samsudeen was found guilty in the High Court of possessing undesirable publications, knowing and neglecting to help the police in carrying out their search warrants.

[30][36][37] On 6 July 2021,[30] Samsudeen was sentenced to 12 months of supervision by a High Court judge due to the length of time he had previously spent in custody.

[30] A pre-sentence report submitted to the court noted that Samsudeen "had the means and motivation to commit violence in the community" and his risk of reoffending was also considered high.

[30] The Department of Corrections turned down an offer by the New Zealand Muslim Association (NZMA) to help rehabilitate Samsudeen following his release, due to his unwillingness to engage with religious and cultural support.

[40] Auckland Mayor Phil Goff vented frustration that the Prime Minister could not share information about the terrorist to the public due to court-issued suppression orders.

[41] On 30 September, the New Zealand House of Representatives passed the Counter-Terrorism Legislation Act 2021, which criminalised the planning of terror attacks and expanded the powers of police to conduct warrantless searches.

[41] Countdown as well as Foodstuffs, which together own the vast majority of supermarkets in New Zealand, removed all sharp knives from sale nationwide as a precautionary measure.

[46] On the evening of the stabbing, the Crown Solicitor applied to the High Court to lift the suppression order concerning the attacker, which was issued in July 2018.