A father has been sentenced to life and ordered to serve a minimum of 35 years after admitting murdering his two young children in their bath.
Perry Samuel, 35, who has manic depression, smothered Aidan, three, and Caitlin, five, at their home in Bodelwyddan, Denbighshire.
Judge John Rogers said he believed Samuel had been motivated by malice against the children's mother.
But Samuel is said to be the only one who knows exactly what happened.
A review of the way council and health authorities dealt with Samuel has begun and is expected to report back later in the year.
Sentencing Samuel at Mold Crown Court, Judge John Rogers said: "You took them one after the other and put your hand over the mouth and the nose, disregarding their desperate struggle to get air into their lungs. You left your hands there until life itself had left their bodies."
"You abused the most important position of trust, that of a father for his children.
Caitlin and Aidan Samuel were described as "little angels"
"I accept you have a mental history which may provide some explanation for your actions although I believe your motivation was simply malice towards these children's mother."
The court heard about the relationship between the children's mother Sarah Graham and Samuel, and were told that at one point they had split up, with Samuel becoming depressed about that.
But at the time of the murders, they had reunited - although Samuel had looked at text messages on Ms Graham's mobile phone and might have suspected she was seeing a male friend.
Defence counsel Stephen Riordan QC said that the truth of what happened "remains in his (Samuel's) head"
Samuel had told police the children had been having a bath and he remembered smoking a cigarette on the doorstep, hearing playful splashing upstairs.
Mr Riordan said he told police that then "everything went wacko."
"He can remember kneeling alongside the bath and falling against the wall. His jumper was wet and he took it off. The children were in the water," the barrister added.
Mr Riordan explained that Samuel was too scared to call police straight away. Post mortem examinations suggested the time of death at some time between 2000 GMT and 2130 GMT.
He made a rambling call to the police shortly before 11pm that night.
The children's mother had been at a pop concert in Manchester with friends and had left her partner to care for the children.
In a statement issued after sentencing, Ms Graham said no prison sentence would be long enough to excuse taking away the lives of her "beautiful babies" or to justify the "living nightmare that this man has put me and my family through".
She told the court she wished she could go to sleep and not wake.
Ms Graham said she suffered regular nightmares and her pain would never go.
"Even though we didn't have the perfect relationship, I thought that he loved me and the children and I never ever thought that he would kill his own children," she said.
"My biggest fear throughout this whole nightmare is that the children suffered.
"The police have told me as much as they know, but the only person who can say exactly what happened in my home on the evening of Bonfire Night last year is Perry."