The homes on Monday were searched in the New South Wales towns of Sandy Beach and Lawrence, both near the town of Grafton where Brenton Tarrant, the alleged attacker, grew up.
“The primary aim of the activity is to formally obtain material that may assist New Zealand police in their ongoing investigation,” a police statement said.
Tarrant’s family “continues to assist police with their inquiries” and there is no information to suggest “a current or impending threat” to the community, it said.
Tarrant, a self-avowed white supremacist, spent his youth in Grafton but has travelled abroad extensively over the past decade and had lived in recent years in Dunedin, New Zealand.
He has been charged with murder in New Zealand after the mass shooting on Friday that left 50 dead and dozens wounded, many in critical condition, at two mosques in the city of Christchurch.
It was New Zealand’s deadliest shooting in modern history.
Tarrant had worked as a personal trainer at the Big River Gym in Grafton, a small city 500km northwest of Sydney.
Some of Tarrant’s family members expressed shock and sorrow in interviews with Australian media on Sunday.
“We’re all gobsmacked, we don’t know what to think,” Marie Fitzgerald, Tarrant’s grandmother, told Channel Nine television.
“The media is saying he’s planned it for a long time so he’s obviously not of sound mind I don’t think. It’s only since he’s travelled overseas that that boy has changed completely from the boy we knew. Now everyone’s just devastated,” she said.
In 2016, Tarrant visited Serbia, Montenegro, Bosnia and Herzegovina, and Croatia, where he stopped by historic battle sites, before travelling in Western Europe in 2017. He also visited Turkey, Bulgaria and Israel.
“We say sorry for the families over there for the dead and the injured. I can’t think nothing else. I just want to go home and hide,” said the alleged attacker’s uncle, Terry Fitzgerald.
Australian Home Affairs Minister Peter Dutton said on Monday that Tarrant had spent only 45 days in Australia over the past three years and was not on any “terrorism” watch lists.
He rejected as “disgraceful” criticism that Australia’s counterterrorism agencies had neglected the threat of right-wing “extremists” such as Tarrant because of their focus on combatting groups such as al-Qaeda and Islamic State of Iraq and the Levant (ISIL, ISIS).
He said the Australian Security Intelligence Organisation (ASIO), the country’s main security agency, closely tracked the activities of far-right groups.
“These extremist groups – neo-Nazis, or white supremacists, extreme right-wing groups, whatever term you want to apply to them – they’ve been squarely on their radar,” he said in a televised interview.
“They are well and truly looking at this threat, they are dealing with the threat and to think that they’ve just discovered it or they are coming late to the party is complete rubbish,” he said.
ASIO officials were due to brief the cabinet of Prime Minister Scott Morrison on the New Zealand attacks and the threat of the far right in Australia later on Monday.
Australia is making public grants available to help places of worship bolster security after Friday’s attack in neighbouring New Zealand.
Morrison said $39m in total will be made available to add security video, fencing, lighting and alarms. He said religious freedom has to start with the right to worship and meet safely without fear of violence.