A 40-year-old man with no fixed address has been arrested in connection with the murder of an elderly couple in Groningen, news agency ANP reported.

Police launched a double murder investigation after the bodies of a couple were found in a canal, close to where their boat was moored. No more details were given about the man, ANP said.

Lammert and Marga Westra disappeared on Monday afternoon after going to show their small motorboat to a prospective buyer. Their children raised the alarm after the couple, aged 68 and 70, did not return home.

Police found their bodies in the water on Tuesday and confirmed they had been killed.

The Telegraaf describes the couple as well-known in the north Groningen village of Aduard. They had two dogs and took part regularly in village events. Neighbours told the paper they never saw ‘strange people’ visiting them. Lammert Westra, a former carpenter, retired several years ago.

‘Who would do such a thing? Was it for money?’ one neighbour said. ‘They were not rich.’