Four-year-old Daniel Pelka's life was one of such "extreme cruelty" in the run up to his death that a sibling felt compelled to hide food for him while he was being starved by his parents.
Daniel was denied food, force-fed salt, held under the water in a bath until unconscious and regularly beaten.
He was also imprisoned in a box-room and died alone in the dark from a head injury in March 2012.
Despite appearing to be a happy little boy when he started school in Coventry, teachers saw Daniel become "thinner and thinner in front of their eyes" and said his uniform was "hanging off him".
Jurors at Birmingham Crown Court heard he looked like a concentration camp victim; his lunchbox contained half a sandwich and he tried to eat food from school bins.
'Bashed against wall'
His mother, Magdelena Luczak, 27, and her partner, Mariusz Krezolek, 33, have been convicted of murdering Daniel, who died in Coventry last year.
At the time of his death, Daniel weighed just over a stone and a half - and had suffered a catalogue of injuries.
The court was told how the sibling would often ask for extra food to give to Daniel.
"I had my money I got from the bank. I found a card on the floor. I used to go to a shop with my brother and used to buy things for him that [Luczak] couldn't see," the child said.
"I had to make food for him, I had to clean him up."
The sibling, who cannot be identified, also told the court about Daniel being held under the water in a bath at the family home.
"[Krezolek] bashed Daniel's head against the bath. He pushed him.
"[Luczak] was holding him under water. [Krezolek] told me not to tell anybody. Daniel cried. They didn't do anything," the child added.
The child also said Daniel was not allowed to leave his bedroom to use the toilet and was expected to defecate in his bed.
'Bag of bones'
Senior investigating officer Det Insp Chris Hanson, from West Midlands Police, said: "We'll never understand why they did what they did to Daniel.
"They turned Daniel from a beautiful, bright-eyed little boy into a bag of bones basically and broke him in so many ways."
Police said there was a "very thin" mattress on the floor of the box-room in the small rented terraced house, but there was no furniture and there were no toys, "just some very thin threadbare carpet, which was heavily urine-stained".
Det Insp Hanson said Daniel spent several months there with no heating and no pictures on the walls.
He said he would have slept there "during what was a pretty harsh winter" and if he was not at school, was "basically kept locked in his room", where the door handle had been removed.
Police found a child's handprint where the handle should have been.
When Daniel died he weighed a little over a stone and a half - the average weight of an 18-month-old baby, police said.
Teaching assistant Amy Tokely broke down in tears in court, when she said he wanted to eat "muddy and dirty" pancakes which had been on the floor.
Daniel's mother claimed he was being treated for a rare eating disorder and school staff were not to feed him. They complied with her instructions.
The family also had contact with social workers, doctors, health visitors and police.
Education officials investigated Daniel's poor school attendance and health visitors went to the home but never saw him, the court heard.
'Web of lies'
A serious case review, involving agencies that had involvement with Daniel, is due to be published in a few weeks.
The boy had more than 30 separate injuries to his body, the murder was planned and "protracted", and Luczak especially told a "web of lies", police said.
Luczak said the boy had special needs or learning difficulties which were genetic and inherited from his father.
But Daniel's father, Eryk Pelka, told officers that was "completely untrue", the force said.
Det Insp Hanson stated there was "absolutely no evidence" of an eating disorder and he believed Luczak made the story up to conceal the fact Daniel was being starved.
Text messages between unemployed Luczak and factory worker Krezolek confirmed their abuse. They revealed "premeditated, prolonged cruelty" and a "significant element of teamwork" by two very strong characters, police said.
In one text, Luczak wrote: "We [will] deal with [Daniel] after school he won't see grub at all."
In another, Krezolek said: "Take him to the room and lock him there, you'll have some peace."
The force also said it uncovered "telling and compelling Google searches" where someone, "either or both, had made inquiries on how to poison someone with salt [and] how to deal with a child that has water in their lungs".
Eryk Pelka said Luczak had moved to England with him in 2006 and Daniel was born soon after they arrived in Coventry.
They moved frequently because of her demands for a bigger house.
Their relationship ended when she had an affair, but Daniel's father said he had no clue she and her new boyfriend could be so cruel.
Mr Pelka said: "I could not believe that they could do something like that to my son, make him starve and I felt anger. I just hate them."
Police were involved with Daniel over a broken arm he suffered in 2010, but decided not to press charges.
The force said it was the "right decision" not to prosecute, saying the parents had told officers Daniel had slid off the back of the settee and on to the floor, which was "consistent" with the injury.
The incident was referred to social services, which then began to work with the family and completed an assessment in relation to Daniel.
Det Insp Hanson said: "Of course, at that stage 18 months before his death, we were dealing with a rather bright-eyed and plump little boy."
He added the couple had been living at the address for more than two years and he believed police were called twice over "verbal arguments only".
Coventry Safeguarding Children Board has commissioned a serious case review, which will include new information which emerged during the trial.
Det Supt Tim Bacon, from West Midlands Police's public protection unit, said: "It is absolutely right that people are outraged and want to know could it have been prevented and I think the purpose of the serious case review is to do exactly that."