An elderly couple with dual British and Spanish nationality have been found dead at their holiday home in France after what police believe was a murder-suicide.

Jon and Carlotta Ortuzar were found at their house in Urrugne, in the Basque Country near the border with Spain. Investigators believe Mr Ortuzar, 76, strangled his 60-year-old wife before drowning himself in their swimming pool.

A letter in Spanish, thought to have been written by Mr Ortuzar, was found at the scene, and although its contents have not been revealed, an official described it as “explanatory”.

According to the Sud-Ouest newspaper the couple, whose main residence was in Madrid, were last seen alive on Sunday, when they attended church.

On Tuesday a cleaner arrived at their home and found Mr Carlotta at the bottom of the swimming pool with weights tied to his waist. His wife was found in her bedroom with bruises on her face and an elastic cord around her neck. A hammer was found next to her.

Odil de Coral, the mayor, said the community was shocked by the deaths of the couple.

“I went to the house straight away to offer my support to the brother (of Mr Ortuzar) and the nephews of the victims, who have also made Urrugne their second home,” he told Sud-Ouest.

“Jon and Carlotta came very often to the Basque country, where they bought this house just after the War.”

Mr Ortuzar was born in London to a family of Basque nationalists who had fled Franco’s regime in Spain, and though he and his wife lived predominantly in Madrid, he retained his British nationality. He also worked in the City of London for some time.

Police found no evidence of a struggle at the couple’s house, known as Xandiru Baita, and nothing appeared to have been stolen, leading them to the murder-suicide theory.

A friend of the couple, Daniel Poulou, said: “They were charming people, who loved having guests round and knew how to treat them. They got on really well.

“They had no children, but they were very close to Jon’s brother and his children.”

A Foreign Office spokeswoman said they had not been informed of the deaths, but added that this was often the case where people had dual nationality.

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