The mother and stepfather of five-year-old Logan Mwangi whose battered body was found dumped in a river have been jailed for life for his murder.

John Cole, 40, was told he would spend at least 29 years behind bars while Angharad Williamson, 31, would serve a minimum of 28 years.

A 14-year-old boy, who cannot be named because of his age, was detained for a minimum of 15 years after also being found guilty of Logan’s murder.

The trio were convicted of killing the little boy in Sarn, Bridgend, South Wales, in April, following a trial at Cardiff Crown Court.

Passing sentence on Thursday, Mrs Justice Jefford said: “You are responsible for Logan’s death and all the anguish that has followed from it.

“Because he was killed in his own home, it is not possible to be sure what has happened to him.

“Shortly before his death, at which time he was three feet five inches and weighed only three stone one pound, he was subjected to a brutal attack.”

The judge described the injuries Logan had suffered and added: “Also the sort of injuries seen in abused children.

“Inflicting these injuries on a small, defenceless five-year-old is nothing short of horrific.”

Both Williamson and the youth were convicted of a further charge of perverting the course of justice – an offence Cole had admitted before trial.

Logan, a previously “smiling, cheerful little boy”, was discovered in the River Ogmore in Pandy Park on the morning of July 31 2021.

Police found him partially submerged, wearing dinosaur pyjama bottoms and a Spider-Man top just 250 metres from his home.

The youngster had suffered 56 external cuts and bruises, and “catastrophic” internal injuries, which were likened to a high-speed road accident.

Experts said the injuries could have only been caused by a “brutal and sustained assault” inflicted on Logan in the hours, or days, prior to his death. They also said the injuries were “consistent with child abuse”.

In the months and weeks leading up to his death, Logan had been “dehumanised” by his family, prosecutors said.

Logan’s stammer is said to have worsened, becoming particularly bad around Cole. He wet himself more frequently and began self-harming.

Friends of the couple said Cole told them he did not like Logan, and others said his attitude changed after becoming obsessed with the idea that Williamson had cheated with Logan’s father Ben Mwangi.

After Williamson gave birth to his own child, Cole was reluctant to let Logan see the baby and later claimed the boy had tried to smother the infant.

Medics made a safeguarding referral to the police after Logan suffered a broken arm in August 2020.

By March, due to concerns over Cole’s behaviour, Logan and his younger sibling had been assigned their own social worker.

In June, a month before Logan died, the family were removed from the child protection register – meaning it was believed there was no longer a risk of significant harm.

A foster family whom the youth stayed with claimed to have heard him say he wanted to kill Logan.

A support worker also heard the youth singing: “I love kids, I f****** love kids, I love to punch kids in the head, it’s orgasmic.”

Weeks before he died, Logan suffered a broken collarbone but he never got medical treatment.

On July 20, Logan tested positive for Covid-19 and he was shut in his bedroom with a baby gate barring him from leaving.

Caroline Rees QC, prosecuting, said: “He had been kept like a prisoner in his small bedroom in the flat you saw, a room likened by Williamson as a dungeon.”