24 Hours in Police Custody is back with a gripping two-part special, A Family Vendetta, shining a spotlight on the chilling crimes of double murderer Stephen Alderton. Viewers are already asking the big questions. What exactly did Stephen Alderton do, why did he do it, and where is he now?
The new instalment, airing from Monday (December 08, 2025), dives deep into the investigation surrounding the fatal shootings of father-and-son duo Josh Dunmore, 32, and his 57-year-old dad, Gary, in Cambridgeshire. What begins as a heartbreaking double tragedy soon unravels into a dark and complex family feud.
It’s not long before detectives identify the killer as 67-year-old grandfather Stephen Alderton, whose actions stunned both the local community and officers working the case. The documentary tracks how police pieced together his movements, the motive behind the attack, and the painstaking work that led to his arrest.
So where is Alderton now, and what consequences did he face for the murders? Here’s everything you need to know as the series lifts the lid on one of its most shocking stories to date.
24 Hours in Police Custody: A Family Vendetta on crimes of Stephen Alderton in Cambridgeshire
The latest episode of 24 Hours in Police Custody examines the brutal murder of 32-year-old Josh Dunmore and his 57-year-old father Gary. A gunman shot both men dead with a Beretta shotgun at point blank range at their homes. They lived in villages six miles apart in a quiet part of Cambridgeshire. The murders had all the characteristics of an execution. The reason? It eventually became apparent that the killings were over a dispute about the custody of a child.
On the evening of March 29 2023, police received a 999 call to an address in the quiet Cambridgeshire village of Bluntisham. Concerned neighbours made the call after hearing a shotgun. A synopsis for the two-parter tells us: “A man has been fatally shot. And the perpetrator has fled the scene. Within minutes, a new emergency call was received. There’s been another shooting in the village of Sutton just a 10-minute drive away. A second victim is discovered fatally wounded.”
Police were shocked to discover that the new victim was the father of the first man found dead. Detectives from the Major Crime Unit soon established that the motive for the double murder could lie in a dispute over who should have custody of the child of the first victim.
As the investigation continued, police identified two potential suspects, sparking a double manhunt. They subsequently discovered that their first suspect was holed up in a nearby hotel with the mother of the child. Meanwhile, the second suspect – the grandfather of the child, Stephen Alderton– was heading to the west in a camper van. Crucially, police knew he was still armed.
Who killed father and son Gary and Josh Dunmore?
Stephen Alderton shot and killed Josh Dunmore and his father Gary in cold blood. He murdered the two men at separate properties in two Cambridgeshire villages in March 2023.
Prosecutor Mr Gair later said that Alderton had a shotgun licence. He lawfully held a Beretta shotgun which was used in both killings. He said it was likely the killer had knocked on Josh Dunmore’s door and shot him “twice at close range” when he opened it.
Stephen Alderton later drove six miles to Gary Dunmore’s house and shot him three or four times at close range. There was 40 minutes between each murder.
Gary Dunmore’s mother gave an victim impact statement during Stephen Alderton’s trial. She said: “Both were killed in the most vicious, cowardly way. There was no opportunity for self-defence.”
Police also arrested a 28-year-old man and 33-year-old woman from Mildenhall, Suffolk, on suspicion of conspiracy to murder. They were previously on bail until December 7, 2023, and were re-bailed until March 2024. A Cambridgeshire Police spokesperson subsequently confirmed they were re-bailed again until June 2024.
Who is Cambridgeshire shooter Stephen Alderton?
Stephen Alderton was a widower, and former chartered quantity surveyor. He was also father to Samantha Stephen, nee Alderton, and a grandfather to her then-seven-year old son. Samantha had joint custody of her son with former partner Joshua Dunmore.
Stephen had no fixed address and lived in a white Peugeot motorhome. Before killing Josh and Gary Dunmore, he’d never had a criminal record, and claimed to be a “a respectable, law-abiding citizen all my life”.
Alderton’s wife had died in December 2019. He subsequently sold his home and was living at the time of the offences in a motorhome on a site in Willingham, Cambridgeshire.
Why did Stephen Alderton shoot Josh and Gary Dunmore?
An ongoing family court case triggered the tragic events of March 29, 2023. Detectives established that the motive for the double murder lay in a dispute over who should have custody of involving Stephen Alderton’s grandson. The boy was Josh Dunmore’s child.
The killings came two days after a family court hearing. The court heard how Joshua Dunmore and Stephen Alderton’s daughter, Samantha Stephen, had split shortly after the birth of their son.
In 2020, Samantha remarried American national Paul Stephen who served with the US Air Force. The couple asked the family courts for permission to take the child with them when Paul was redeployed back to America.
However, Joshua opposed the application and on March 27, 2023 – two days before the shootings – the court made an interim ruling the child could not be taken out of the country.
Prior to the ruling, Alderton had written in text messages that he would “override any court decision” and that there was “always a plan B”.
How did police catch him?
Police “rapidly identified” Stephen Alderton as a suspect after the shootings due to the family court case and sightings of his white Peugeot motorhome. Officers used automatic number-plate recognition (ANPR) cameras during their pursuit.
Armed police arrested Stephen Alderton in his motorhome on the M5 near Worcester at about 1.30am on March 30, 2023 – just hours after the murders. Police found a bag of shotgun pellets in the motorhome following Stephen’s arrest, according to news reports at the time.
He told police at the time: “Sometimes you have to do what you have to do even if it’s wrong in the eyes of the law.”
Det Ch Insp Katie Dounias, from the major crime unit, said Alderton had “turned a family dispute into a double tragedy by his rash and brutal actions”.
Where is Stephen Alderton now?
Grandfather Stephen Alderton, who shot father and son Gary and Josh Dunmore dead, is currently in prison serving a life sentence. During his trial, he pled guilty to both murders.
A judge at Cambridge Crown Court sentenced Alderton, 67 at the time, to life with a minimum of 25 years in October. In January 2024, the Court of Appeal extended his sentence by five years to a minimum of 30 years (minus time already served in custody).
Solicitor General Robert Courts KC MP said: “Stephen Alderton’s brutal killing spree has ripped apart a family. I welcome the court’s decision to extend Alderton’s sentence. I hope it sends a clear message that those who commit murder will face the full force of the law.”
Judge Mark Bishop compared the killings to an “execution”. He added: “You took the decision to take the law into your own hands and end the lives of two innocent men.”
In a letter to the court, Stpehen Alderton wrote: “I am not the person that this conflict and the family courts have driven me to become. If I could turn back time I would. I regret there are not enough words of remorse I can offer to the families affected by this crime.”
The court heard how Alderton had later written a letter in which he said he had “never been a violent person”. He is now 68 years of age.
Where is Stephen Alderton’s grandson now? What happened to him?
Police chose not to disclose the identity of Stephen Alderton’s grandson, protecting the privacy of the seven-year-old boy who had already endured unimaginable trauma. At the time of the shootings, the child had not only lost his father but learned that his own grandfather was responsible.
During the court hearings, it emerged that the youngster had been taken into care in the aftermath of the murders. The revelation added another heartbreaking layer to an already devastating case, highlighting the ripple effects of Alderton’s actions on the wider family.
However, it’s not known now whether he was returned to the care of his mother.
Read more: 24 Hours in Police Custody viewers declare ‘they’re guilty, lock them up’ as pet dog kicked by gang
24 Hours in Police Custody: A Family Vendetta airs on Monday, December 08, and Tuesday, December 09, at 9pm on Channel 4.
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