The Christchurch mosque gunman idolised Adolf Hitler and other prominent fascists, an inquest has heard.
An expert in firearms handling and control also told the inquest the terrorist showed an amateurish level of skill in operating his weapons on 15 March 2019 but was still able to kill dozens of worshippers in minutes due to semi-automatic mechanics of his primary weapons and their high-capacity magazines.
On Tuesday, the inquest into the deaths of 51 people massacred at Al Noor Mosque and Linwood Islamic Centre in March 2019 heard evidence from the terrorist's sister, Lauren Tarrant, and Shane Hepi, an expert in small arms use.
Hepi, a qualified NZSAS instructor, said Brenton Tarrant was an amateur in handling small arms.
"The offender was well equipped with lethal weapons, ammunition and equipment, however, he displayed very low proficiency when employing these items, including how he prepared, conducted and post conducted himself," Hepi told the inquest.
"The offender easily controlled the environment given his victims were defenceless, unexpecting, trapped, and unarmed. Despite this advantage, the offender performed in a chaotic, unskilled, cumbersome and non-proficient manner."
Hepi had reviewed footage of the shootings and said his analysis showed the terrorist had some training with firearms, but lacked fundamental skills, knowledge and proficiency.
"I am highly confident in concluding that the offender has not had any formal intermediate or advanced weapon handling and control training, with any of the weapon systems employed during the attack. The offender's abilities are very low level and lacked any form of proficiency."
Despite that, the terrorist was able to murder 51 worshippers in about a quarter of an hour across two sites which were about seven minutes apart when driving.
Hepi told the inquest the lethality of the attack was due to the two semi-automatic AR-15-style firearms the terrorist used and because his victims were defenceless and trapped.
"A lot of his victims were engaged within the mosque and they were grouped," Hepi said.
"The distance was zero to three metres, and with the fear, shock and panic of the victims all grouping in a contained area, that's where most of the killing was done - when they were grouped.
"That was the advantage he had - they were contained in two large groups - contained, trapped, scared - all trying to muster in a corner of the room, there was no escape. All he had to do really is pull the trigger and ... it just keeps going."
The terrorist used two AR-15-style semi-automatic centrefire rifles, as well as two shotguns - one pump-action and one semi-automatic, a lever-action rifle and a bolt-action rifle.
The capacity of the semi-automatic centrefire rifles' magazines was also a factor.
The inquest had heard the terrorist was able to buy high-capacity magazines because they were not regulated.
By inserting those magazines into the semi-automatic centrefire rifles - which he legally bought with a New Zealand firearms licence - he had in essence built his own "military-style semi-automatic" weapons, which were meant to be more rigourously and tightly controlled at the time of the attack.
"I don't think he would've carried out the atrocity he did with those small magazines to the level he did," Hepi said.
The terrorist's sister's evidence brief was also read to the court.
The terrorist had changed by the time he returned in 2016 from travelling abroad, she said. He idolised Adolf Hitler and British fascist Oswald Mosley.
Around that time he had shaved his head, which she saw as a "further sign of his Nazi interests".
He had started to show an interest in firearms after moving to New Zealand in August 2017 and discussed with his sister how AR-15s were the preferred firearm of choice for mass shootings in the US.
"His use of firearms seemed to go hand-in-hand with what he was spouting and discussing with people online," she told police in an interview following the shootings.
The terrorist "always spoke of a race war".
She imagined, if anything, he would get caught up in the actions of others and go along with them.
"It never entered my thoughts that he would take the step by himself and act as a lone wolf," she said.
His sister believed it related back to his childhood and playing first-person shooter games.
While playing the terrorist would "rage, kick things over, scream at the screen and throw the headsets at others he played with".
She spoke to the terrorist the night before the attack and during the conversation he told her he loved her twice, which she thought was out of character.
"He was calmly spoken and showed no indication of his intended actions the following day," she said.
"He was calmer than normal."
The inquest continues.
Sign up for Ngā Pitopito Kōrero, a daily newsletter curated by our editors and delivered straight to your inbox every weekday.