A recent US serviceman was among three people arrested in connection with the murder of a father and son at separate addresses in rural Cambridgeshire.

The three had been arrested in an operation by armed police following the discovery on Wednesday evening of the bodies of Gary Dunmore, 57, and his son Joshua, 32, at their homes six miles apart.

The serviceman, 27, is believed to have been a member of the United States Air Force stationed in the UK.

Police continued to question the three on Friday.

The body of Joshua Dunmore was found at an address in the quiet village of Bluntisham just after 9pm on Wednesday, while his father was found dead at a house in Sutton at around 9.37pm.

It is understood Joshua Dunmore had been involved in a custody dispute with his former partner, which had only been very recently resolved in his favour.

Police had described the attack on the pair as “targeted”.

Shortly after the deaths a 27-year-old man and his 33-year-old girlfriend were arrested at a hotel outside of Cambridge, according to Cambridgeshire Constabulary.

A 66-year-old man was arrested at the wheel of a vehicle, which was stopped by West Mercia police as it travelled along the motorway in Worcestershire. Officers used a stinger device to stop a white Peugeot 208.

Officers recovered a shotgun, with the driver subsequently transported to Cambridgeshire for questioning.

All three individuals were initially held on suspicion of conspiracy to murder.

A source told The Telegraph that the 27-year-old was “ex-US military” and that the pair had been planning to take the child to the USA.

Police had said on Thursday that the suspects were “known to the deceased and had recent contact with them”, and confirmed “a familial issue” was the “primary line of investigation”.

Officers investigating the deaths gathered CCTV footage for possible evidence from homes close to both Mr Dunmore and his father, who ran a building firm popular in the area.

Their deaths stunned the local communities, with friends and well-wishers gathering to lay floral tributes outside their homes throughout Thursday.

A message left with flowers outside the home of Joshua Dunmore in Meridian Close, Bluntisham, read: “So sad to be taken like this and a little boy now with no daddy. Thinking of the family. RIP Josh.

A floral tribute to Gary Dunmore, left outside his home in The Row, Sutton, said: "To my dear neighbour Gary.

"A man who loved his family dearly, a dear friend to all, so helpful and kind and was always around as a friend and my little odd job man.

"I'm going to miss you."

A further tribute said: "RIP Gary. Absolutely gutted."

Post-mortem examinations will take place in the coming days.