Two children and their father found dead in a car in an isolated beauty spot died from carbon monoxide poisoning, police have confirmed.
Brian Philcox, 52, is thought to have taken his children to the beauty spot in the Conwy Valley and gassed them.
His body was found in a Land Rover with his son Owen, aged three and his daughter Amy, aged seven.
Police said all three from Runcorn in Cheshire had died from poisoning due to inhaling car exhaust fumes.
Officers were alerted at about 1500 BST on Sunday by a passer-by, who found the car off a hillside road near Llanrwst on Father's Day.
Footage of forensic investigation into Conwy deaths
It was parked on a road leading from the A470 between Tal-y-cafn and Maenan.
Police said Mr Philcox had picked up Amy and Owen from an arranged access visit on Friday.
Det Ch Insp Wayne Jones from North Wales Police said Mr Philcox and the children had been reported missing on Saturday night and police in Cheshire had been looking for them.
He said there had been sighting of the three at Llangollen on Saturday.
Mr Philcox, a karate expert, had told friends he planned the visit because the children were interested in trains.
The post mortem examination at Ysbyty Glan Clwyd showed they all died of carbon monoxide poisoning and further toxicology test are still going on. A pipe had been placed from the exhaust of the Land Rover in through the back window said police.
Det Ch Insp Jones said there were no other injuries on the children.
He added: "It is a difficult case for all involved" and said the mother of the children was being looked after by family liaison officers.
"Obviously, as the mother of the children who were killed, she is devastated, she has suffered this double loss.
"She is being looked after by family liaison officers who are giving her comfort and support at this time, and she does have a good network of family and friends around her but obviously this is a tragic loss that she's suffered."
Brian Philcox was a karate expert
He added the police were still keen to hear from anyone who might have seen the three between Friday night and Sunday afternoon in order to establish a timeline of events in north Wales and Cheshire.
The officer also confirmed a bomb disposal unit was called to check out the vehicle after Cheshire Police officers found a "hoax device" at Mr Philcox's home address in the Windmill Hill area of Cheshire.
A section of the road remains cordoned off a while police examinations continue, the force said.
They have also conducted house-to-house inquiries.
The Land Rover has been taken from the scene to St Asaph and will be subject to further forensic examinations by experts.
Tributes have been paid by neighbours of the children near their home in Runcorn.
Nine-year-old Emma McGhee a friend of the young girl who died said: "She was always happy and I had lots of fun with her".
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