Family members of the Australian man charged with murdering Muslim worshippers at two mosques in New Zealand are devastated one of their own could be involved in a massacre.

Brenton Tarrant’s grandmother, Marie Fitzgerald, said the family was gobsmacked he’d been charged over Friday’s shooting attacks on mosques in Christchurch.

“It’s just so much of everything to take in that somebody in our family would do anything like this,” the 81-year-old woman told Nine News in the NSW city of Grafton on Sunday.

“The media is saying he has planned it for a long time so he is obviously not of sound mind.”

Tarrant went to Europe after his father died of cancer in 2010 and came back a different man, Mrs Fitzgerald said.

“It’s only since he travelled overseas I think, that that boy has changed completely to the boy we knew,” she said.

His uncle Terry Fitzgerald apologised on behalf of the family for his nephew’s alleged murderous act.

“We are so sorry for the families over there, for the dead and the injured,” Terry Fitzgerald said.

“What he has done is just not right.”

Tarrant spent most of his time on computer games during his high school days, rather than chasing girls, his grandmother added.

The family had dinner with Tarrant in Grafton a year ago for his sister’s birthday.

His sister and mother have been put under police protection after Friday’s attack, which has left 50 dead and others in a critical condition on hospital.

Meanwhile, counter-terrorism police raided two homes on the NSW mid-north coast on Monday as part of investigations into the shootings.

Officers from the NSW Joint Counter Terrorism Team searched a property in Sandy Beach, near Coffs Harbour, about 8.30am on Monday, before storming a second house at Lawrence, near Maclean.

“The primary aim of the activity is to formally obtain material that may assist New Zealand Police in their ongoing investigation,” the Australian Federal Police and NSW Police said in a joint statement.

“The community can be assured that there is no information to suggest a current or impending threat related to this search warrants.”

Tarrant was not on any watchlist in Australia or New Zealand, despite online profiles linked to him containing white supremacist material

The 28-year-old posted a 74-page document online before the attack. A 17-minute video of the shootings was also live-streamed.

The JCTT is made up of officers from the AFP, NSW Police, as well as ASIO and the NSW Crime Commission.

–AAP