The mother and stepfather of a five-year-old boy whose battered body was found dumped in a river have been found guilty of his murder.

John Cole, 40, and Angharad Williamson, 31, of Sarn, Bridgend, were convicted of killing Logan Mwangi by a jury of five men and seven women at Cardiff Crown Court on Thursday after five hours of deliberation.

A 14-year-old boy, who cannot be named because of his age, was also found guilty of murder.

Williamson screamed “no, no, no” and fell to the floor as the verdicts were returned.

Judge Mrs Justice Jefford had to interrupt the jury and the clerk to tell Williamson to be quiet before the verdict against the youth was given.

“Out of respect for your son and the youth, please be quiet for the verdicts,” she said.

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

Gasps and sounds of celebration were heard from family and friends in the public gallery as the verdicts were returned.

Logan’s father Ben Mwangi was also in court to hear the jury return its verdicts.

The youth was present in the dock for the first time, having previously followed the trial by video link.

There were six custody officers present, more than at any point during the trial.

As Williamson was led from the dock, she struggled with the custody officers and shouted at Cole: “You lying motherf****** murderer.

“You liar.”

Logan, a previously “smiling, cheerful little boy”, was discovered in the River Ogmore in Pandy Park, Bridgend, South Wales, 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 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 Mr 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, with Williamson saying he had fallen down the stairs.

She took him to hospital the day after the incident and said she thought he had only dislocated his shoulder and had tried to put it back.

Later she told a friend the youth had confessed to pushing Logan down the stairs but it was not until January last year she told the police.

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

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 the youth stayed with claimed to have heard him say he wanted to kill Logan.

They said they reported the teenager’s “desire for violence” and threats to harm Logan to his social worker Debbie Williams but that she seemed unconcerned. Ms Williams denies this.

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.

Prosecutor Caroline Rees QC 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.”

Williamson claimed that two days before Logan’s body was found, an argument about a spilt drink escalated and ended with Cole and the youth attacking him.

She accused Cole of punching Logan twice in the stomach and ordering the youth to “sweep” Logan if he stuttered or flinched.

Moments later the youth carried out the martial arts-style manoeuvre, kicking Logan’s legs out from under him while using his hand to slam his head to the ground.

Williamson claimed she screamed for them to stop but said Cole replied: “The only way this boy understands is pain.”

Two days later, she phoned the police at 5.45am reporting Logan missing – claiming to have awoken to find him gone and accusing a woman of taking him.

Police arrived at the flat to find Williamson hysterical, while Cole and the youth could be seen walking around the area calling for him.

Prosecutors said this was part of an “elaborate” cover-up concocted by the defendants and all three were accused of perverting the course of justice, of which Williamson and the youth were convicted.

Cole, who was captured on CCTV carrying Logan’s body to the river from the flat, while being followed by the youth, admitted the charge.

He claimed he woke to the sound of Williamson screaming Logan was dead and he panicked.

CCTV shows a bedroom light being switched on and off while Cole and the youth were out – the prosecution used this evidence to show Williamson was awake and aware Logan was dead.

Cole said after dumping the boy’s body, Williamson sent him out again to hide his ripped pyjama top.

The youth never gave evidence in the trial.

Mrs Justice Jefford adjourned the case for sentencing at a date to be fixed.

At times during the trial, members of the jury became distressed at the evidence presented to them.

The judge thanked them for their “exceptional public service” in trying the case, and listening to “very unpleasant and emotional evidence”.

She added: “It is no less than Logan Mwangi deserved following his death aged five.”

The judge told jurors she has made an order excusing them from ever serving on a jury again if they do not want to.