The rural property remained guarded by police officers from Wairoa pending the arrival of forensics experts to examine the scene, a house about 200 metres from the road.
Police acting on a request from the arrested man took his pet black and white jack russell terrier to friends at Raupunga, on State Highway 2 about 11km west of the scene.
Ngaire Culshaw, a community leader and recently elected to the Ngati Pahauwera Development Trust, was yesterday afternoon looking after the sprightly pet pending passing it on to her father-in-law and spoke of the community's shock.
She said the arrested man had moved home from Auckland several three years ago to care for his ailing mother, who ultimately died in May last year.
Understood to be his only son, the dead man had moved from Auckland more recently so the father could try to help him overcome serious drug problems.
But people in the community were aware it was tough, that there had been at least one incident in which the son had presented a firearm in the house, and the son's issues needed professional help.
"He was doing the loopiest things," said Ms Culshaw, who has worries about other drugs issues in the district.
"His father tried to help him, but I think [the son] was too far gone. The son was out of his league."
She remembered the father saying: "That's my son, I've got to help him . . . as any father would."
"It's a tragedy," she said. "He's a neat old guy, who just came back to Mohaka to look after his mother."
New Wairoa District councillor Charles Lambert, who also lives on Mohaka Township Rd, told NZME: "Since he's been living here he's got on with everyone, he knows our community well.
"It's shocking, it's really terrible."