A “cheerful” and “kind” five-year-old boy was killed by his mother, step-father and a teenager while self-isolating with coronavirus, Cardiff Crown Court has been told.

Logan Mwangi was found dead after being dumped in the River Ogmore near his home village of Sarn in Bridgend County on July 31 2021.

He was wearing mismatched pyjamas and had 56 “catastrophic” injuries to his head, face, torso, arms and legs, a jury of seven woman and five men were told on Monday.

Prosecutor Caroline Rees QC said the little boy’s injuries were from “blunt force trauma”, with experts saying they were more consistent with a fall from great height or high speed car crash.

Logan’s mother Angharad Williamson, 30, her partner John Cole, 40, and a 14-year-old boy, who cannot be named for legal reasons, are charged with murdering the youngster between July 28 and August 1.

All three are also accused of perverting the course of justice, including moving Logan’s body to the river near Pandy Park, removing his clothing, washing bloodstained bed linen, and making a false missing person report to police.

Williamson and the youth pleaded not guilty to both offences, while Cole denied murder but admitted perverting the course of justice.

Williamson and Cole were also charged with causing or allowing the death of a child, which they both denied.

Ms Rees said it is the prosecution’s case that Logan had been submitted to a “brutal and sustained assault” by John Cole and the then 13-year-old boy on July 30 while he was “hidden from view, behind closed doors” in the family home in Lower Llansantffraid.

She told the court: “The prosecution’s case is that Logan was murdered and each of these three defendants played their part…”

Ms Rees said Williamson had done nothing to prevent or report the attack on her young son, not even disclosing what had happened when a social worker visited the house on the same day.

The teenager, who had previously made “repeated threats that he wanted to kill Logan and wanted him dead” was described by Ms Rees as a “complex, troubled and violent boy” who had been trained in the martial art of Muay Thai, also known as Thai boxing, to green belt level.

The jury were shown CCTV footage of Cole and the teenager leaving the family home in the early hours of July 31.

Cole was filmed carrying something in his arms, which he later admitted was Logan’s lifeless body.

The pair walked across the river and along a path to the spot where Logan’s body was found, the court was told.

Cole and the boy then returned to the property before heading out again, this time to dispose of Logan’s bloodied and torn dinosaur pyjama top, the court heard.

During this time, a light can be seen switching on and off in Logan’s bedroom, which the prosecution said proves Williamson was awake and knew what had happened to her son.

Ms Rees told the court that evidence from Williamson’s mobile phone, which showed she was awake in the early hours of the morning – after the time she told police she had gone to sleep – also proves her involvement.

Williamson is said to have struggled to raise Logan in the lead up to his death, with her “motherly bond” with her son “significantly fractured” during his time in self-isolation, Ms Rees said.

She added: “Angharad Williamson must have been awake and up and about, fully aware Logan had died and that his body had been dumped in the river by her partner – disposed of like they were fly-tipping rubbish.”

An apparently distraught Williamson reported Logan missing at 5.45am on July 31, accusing a woman she did not like of kidnapping him, the court was told.

Cole and the youth were then caught on CCTV again, this time walking around and calling for Logan, jurors heard.

Williamson’s 999 call and the faked search for Logan were described by Ms Rees as a “callous” and “elaborate” attempt to cover up the trio’s role in his death.

Williamson, dressed in a navy blue blazer and glasses with dark brown hair, appeared distressed as a summary of the evidence against her and the two other defendants was read out.

She began to cry, becoming more upset as the jury was shown a picture of Logan and the circumstances of his death were described.

She sobbed as she was led out of the dock at the end of the hearing.

Cole appeared in the dock wearing glasses and a light grey V-neck jumper over a white T-shirt, while the teenager appeared in a black T-shirt via video link from another room in the court.

Both adults have been remanded in custody since they were charged, while the boy is in local council care.

The trial, expected to last around eight weeks, continues.