A "wicked and controlling" man will be sentenced on Tuesday for murdering his "fun-loving, mischievous" stepson.
Elvis Lee, 34, was found guilty yesterday of murdering Tyler Whelan, five, last March at his home in Sheepwalk, Paston, near Peterborough.
A report published after his conviction found that key opportunities to protect Tyler were missed by authorities tasked with his care.
It acknowledged that previous incidents in which the boy had been hurt had been "seen in isolation" with "minimal attempts to link concerning patterns of injuries".
The court heard unemployed Lee kicked and bit Tyler on the day of his death.
The boy's mother, Stephanie Whelan, 27, was found guilty of allowing the boy's death.
The tragedy followed three earlier admissions to hospital - including treatment for a broken leg and injured penis - which had prompted doctors to contact social services.
The serious case review, compiled by the Peterborough Safeguarding Children Board and published after the verdict at Cambridge Crown Court, acknowledged failings by the organisations responsible for his care, including Peterborough Children's Services.
The report concluded that it was impossible to say that, had there been greater intervention, the tragedy would have been prevented.
But the report said: "Whilst it would be very challenging to state with any conviction that the subject's (Tyler's) death was either predicable or preventable, there were certainly numerous missed opportunities when interventions should have been more rigorous and incisive on clear occasions when there were concerns about his safety at home.
"Additionally there were some occasions when initiatives were not taken to assess the levels of risk to the subject when there was a procedural requirement to have done so.
"Even if any of the missed assessment opportunities had in fact been taken and completed in line with procedures, it could still not be said with any certainty that they would have made a difference to the eventual tragic outcome."
Whelan, of Sheepwalk, Paston, but originally from Wigan, and Lee, of Crabtree, Paston, were each cleared of two counts of cruelty or neglect relating to their failure to seek prompt medical attention on previous occasions.
Speaking outside court, Shaun Harrison, Tyler's father, said he held Lee and Whelan entirely responsible for his death. He added he felt no malice towards the rest of Whelan's family.
Harrison, from Wigan, added: "The last year of my life has been unbearable.
"Tyler was a fun-loving, mischievous little boy with a big heart and amazing smile.
"I feel lost without him in my life and I still can't believe he's gone."
Superintendent Simon Megicks, from Cambridgeshire Police, said: "This was a wicked crime in which an innocent five-year-old was murdered by a person who should have been looking after him.
"Lee is a controlling and violent man who lost his temper and inflicted fatal injuries to Tyler.
"Whelan has been found to have allowed his death following these fatal injuries - Tyler deserved more from his mother.
"Every child has the right to be protected and feel safe in their own home and it is a parent's responsibility to ensure this is the case. I hope this verdict brings peace to Tyler's relatives knowing justice has been done."
Whelan sobbed and hung her head as the verdict was delivered.
Lee shouted at jurors and protested his innocence as they left the courtroom.
The court heard Lee, who was himself the victim of abuse as a child, had 56 previous offences, including dishonesty, affray and violence.
Police had been alerted to alleged attacks by him on Whelan but he was never convicted.
During the trial, prosecutor Christopher Donnellan told the court that the boy suffered "non-accidental" injuries including a broken leg and injuries to his penis in the year before his death.
Donnellan said that on the day of his death Tyler was covered in severe bruises after he was kicked, hit and bitten by Lee.
He told jurors that Whelan knew Lee was capable of violence as she had suffered a series of attacks.
Whelan will be sentenced next month. Both she and Lee were remanded in custody.
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