A 27-year-old US Air Force serviceman from Ohio was arrested and later released in the United Kingdom in connection to two fatal shootings of a father and his son this week. 

The US military man, Paul Stephen, his British wife, Samantha Stephen, and her father, Stephen Alderton, were arrested for the double murders but all were released except Alderton. 

British media identified the victims as Samantha Stephen’s former lover, Joshua Dunmore, 32, and his father, Gary Dunmore, 57.

Police found Joshua Dunmore dead in a house in Bluntisham after they received reports of gunshots at around 9 pm on Wednesday, March 29.  His father, Gary Dunmore, was also discovered dead half an hour later in his apartment in Sutton, a few miles away.

Cambridgeshire police released a statement on Friday saying that they had arrested the Stephens couple but had released them. They charged a 66-year-old man, Stephen Alderton, Samantha Stephen’s father, with two murder counts and one count of firearm possession.

On Thursday, Detective Chief Superintendent Jon Hutchinson said the victims were father and son. He said the police were working on establishing if the killings were connected to a custody battle as widely reported.

Chief Hutchinson said that their primary line of investigation was that the slayings were connected to a family issue.

According to The Sun, Joshua Dunmore had won custody of his six-year-old son the day before he was killed. A friend told the paper that Joshua had wanted to stop his former partner, Samantha Stephen, and her American husband, Paul Stephen, from taking the boy to the US and he had been overjoyed by his victory and being able to spend Easter with his son.

Fatal shootings are rare in the UK, with the relative lack of guns by most of the population accounting for the country’s low rate of gun violence.