"Police advised Kim's family of the arrest earlier today.
"Police and the family would like to thank the public and media for their assistance during the investigation into Kim's disappearance."
Richmond was reportedly last seen driving a silver Ford Ranger ute away from the family's remote Arohena farm in the early hours of July 31, 2016.
After months of fruitless searching, the family's hopes were raised when a young girl picked up two bank cards belonging to Richmond on the side of the road near Otukou, on State Highway 46 between Rangipo and State Highway 47.
A farm card belonging to Richmond was also found in the area.
Searchers scoured the area's farmland and bush in the months after Richmond's disappearance, and Lake Arapuni was partly drained to allow divers and the police Eagle helicopter to search for the ute, with no success.
But last week police divers were back at the lake, where the ute was found submerged in a 6m-deep part of the lake with poor visibility.
A crane was used to pull the vehicle from the water. A post-mortem confirmed the body found inside was Richmond's.
She is to be farewelled at a funeral at 1pm tomorrow at Te Awamutu.
Richmond's mother declined to comment today but after the vehicle was found last week she said the full impact had not hit the family yet.
"We're pushing the emotions back. We've had 11 months to deal with this.
"It's not going to show until we actually get Kim back and find that life will never ever be the same. And that's the hard part.
"Life goes on and we have to live without Kim and for us that's really, really hard."
