A report into whether social workers could have stopped a Sawtry teenager killing his girlfriend’s two-year-old daughter has cleared Cambridgeshire Social Services and other agencies of blame – but says lessons must be learned.

Dean Harris, 19 at the time, a former Sawtry Community College pupil, was sentenced to life and told he must serve at least 17 years after being convicted of murder following a trial at Cambridge Crown Court in August.

The court heard that Harris, left alone with the toddler, Amina Agboola, while her mother was taking an older child to school, kicked her 6ft across the room after she had soiled herself.

The force of the blow tore her liver in two. Harris called an ambulance saying she had fallen off the toilet. Amina was taken to hospital but died.

Amina's mother, 28, was acquitted of causing or allowing the death but admitted two other charges of neglect. She was given a suspended sentence.

The report, published by the Cambridgeshire Local Safeguarding Children Board (LSCB) on Thursday (March 19), says the death could not have been predicted or prevented.

It notes that Amina, referred to as 'child H', was found to have had a number of other injuries, including an untreated broken wrist. A GP had referred her for an X-ray which never took place. It is policy for hospitals to alert doctors of non-attendance after six weeks but by then she was dead.

The report says professionals, including a teaching assistant, and a member of pre-school staff, had flagged up concerns about Harris's "rough handling" of children. Because Amina was only two and did not go to school, the report describes her as "invisible".

Harris, who had a police record, was told by social services that he should not be alone with the children. The report says this "verbal action plan" should have been made clearer. He had been heard threatening a child with no food and had shut the door on another so hard he made her nose bleed.

The report recommends that social workers should consider the impact of one family member on the others. It says Harris had a troubled childhood and adolescence. At four he had a serious illness. His parents then separated acrimoniously and he moved between them when his behaviour became too much for one of them to bear. He was diagnosed as having hyperactivity (ADHD) and seen by the Child and Adolescent Mental Health Services for nine years until he was discharged because he was no longer a child. Then his medication stopped.

At 17, he was homeless. He had by then been found guilty of burglary and theft, of destroying and damaging property and of possessing a knife in a public place. He was acquitted of battery in 2012 in a confrontation with his step-father over money.