The pair were mourned by friends and family after their bodies were found on Thursday morning in their burned-out home at Manapōuri, 22km south of Te Anau.
A Fire and Emergency NZ (Fenz) spokesperson today said the investigation was complete.
“The fire was caused by a heater coming into contact with flammable material, likely bedding,” district manager Julian Tohiariki said.
Tohiariki said the house had no working smoke alarms at the time of the fire.
“This was a tragedy for the family and our thoughts are with them and the community of Manapōuri at this difficult time.”
Detective Sergeant Mark McCloy said police, along with specialist fire investigators from Fenz, conducted a full-scale scene examination of the home over the weekend.
“Their bodies have since been transported to Christchurch where a post-mortem examination was conducted,” McCloy said.
“This event was tragic and police continue to ensure there is appropriate support in place for those affected by this terrible event.”
A Givealittle page set up to help Kelly Kemble Kerr’s partner and family following the deadly blaze had raised over $6000 since Sunday.
Lisa Hoeta, who set up the Givealittle page, said she had been best friends with Kemble Kerr for 32 years.
Her last messages from Kemble Kerr had been full of love and pride for her children and grandchildren, including Kelly jnr, a “highly intelligent” boy who had just started making money off his YouTube account.
“She just loved her children so much.”
Kemble Kerr’s partner Jason Hoggard, who also lived at the View St rental home, was away working when the fire began about 3.40am.
Her daughter told Stuff Kemble Kerr had a heart condition, which meant she couldn’t move fast.
“She wouldn’t have been able to escape. It was just really quick.”
Her mum loved reading and writing, and was hoping to buy a house, Manaia Kerr said.
And Kemble Kerr’s namesake, son Kelly, was a creative boy interested in drawing and animating - for which he had his own YouTube channel named The Amazing Animator, Manaia Kerr told Stuff.
Kelly, who was autistic, was “the sweetest boy”, she said.
Her mother liked to leave the fireplace door open, which her daughter thought may have caused the fire.
The house was well alight when volunteer firefighters from Manapōuri and Te Anau arrived, a Fenz spokesperson said.
A crane was used to remove the remaining sections of the home’s roof to allow specialist investigators from police and Fenz to enter the home, McCloy said earlier.