A double murderer who shot his daughter’s ex-partner and his father over a custody disagreement had a “short list of people” he intended to kill.
Josh Dunmore, 32, and Gary Dunmore, 57, died at separate properties in two Cambridgeshire villages on 29 March after Stephen Alderton, 67, blasted them with a shotgun.
The murders came two days after a family court hearing involving Alderton’s grandson, which became “the straw that broke the camel’s back”.
After Alderton was arrested hours later by armed officers on a motorway, he told police that “sometimes you have to do what you have to do even if it’s wrong in the eyes of the law”.
“We say it’s clear that the events were triggered by an ongoing family court case between this defendant’s daughter Samantha Stephen, nee Alderton, and her former partner Joshua Dunmore,” prosecutor Peter Gair said.
“This concerned a request to move their seven-year-old child from the jurisdiction of the court by emigrating to the USA.”
He said that Mrs Stephen and Mr Dunmore’s relationship ended shortly after their son was born and in 2020 she married her current partner, Paul Stephen.
Mr Gair said that Mr Stephen, a US national, served with the US Air Force.
“He was due to be redeployed back to the USA,” said Mr Gair. He said they “sought permission of the family court and Joshua opposed the application”.
“There was a hearing on March 27 2023 and it would appear (the child) wouldn’t be removed from the jurisdiction,” said Mr Gair.
At the time, Alterton was living in a motorhome on a site in Willingham and was the legal holder of a Beretta shotgun.
Previous messages on his phone revealed his interest in court proceedings, in which he sent one message saying: “I will override any court decision”.
He had also written “I’ve a shortlist of people I intend to murder” and had taken photographs of the homes of both Joshua and Gary Dunmore.
On the day of the shootings, he drove his white Peugeot car to the men’s addresses, before making further visits to the properties in the evening.
After Joshua Dunmore’s girlfriend left his home in Bluntisham at around 9pm, Alderton approached the door and shot him “twice at close range” in his chest and head at 9.09pm.
Mr Gair said this would have been “rapidly fatal” while a neighbour saw the defendant “walking from Joshua’s house to his white car carrying a shotgun”.
Just 31 minutes later, Gary Dumore was shot six miles away at his home in Bluntisham, with four shots fired at close range.
Alderton was “rapidly identified” as the suspect due to the family court case and the sightings of the white Peugeot.
He was stopped by armed police from the West Mercia force on the M5 near Worcester at about 1.30am on March 30, police said.
Mr Gair said Alderton was the sole occupant of the vehicle and “he volunteered that the shotgun was in the motorhome which it was”.
Alderton, of no fixed address, pleaded guilty to both murders and has now been jailed for life with a minimum term of 25 years.
In a victim impact statement read to the court, Gary Dunmore’s mother Jane Phillips said: “Both were killed in the most vicious, cowardly way with no opportunity for self-defence.”
Mandy Seamark, mother of Joshua Dunmore, said in a statement read by Mr Gair that “words cannot describe the devastation” of the defendant’s actions.
He said Alderton, who worked for 25 years as a chartered quantity surveyor and had no previous convictions, had pleaded guilty to murder, describing this as a “rare” thing.
He said the defendant was “realistic enough to know… he will never be released from prison”.
Alderton’s letter also said: “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.”
Mr Langdale said the defendant regarded the order from the family court as the “straw that broke the camel’s back” and he had “tried hard to control his anger”.
In a letter, the defendant wrote: “I’m not the person that this conflict and the family courts have driven me to become.
“I’ve never been a violent person, I do not have a criminal record. I’ve been a respectable, law-abiding citizen all my life.
“What happened to me on March 29 I do not know.”
Mr Langdale said Alderton’s grandson has been placed in care and “that’s a further burden upon” the defendant.