Three people found shot dead in Mijas, Fuengirola, Spain, may have laid there for several days.
The British man, his Irish wife and their daughter in her 20s are believed to have died in a murder suicide. The man has been named locally as Philip Wood, while the mother is believed to be Sheila, and the daughter, Sophie Wood. Both of the women were Irish.
Ireland's Department of Foreign Affairs says it is now in contact with the wife's family.
The alarm was raised by the family's landlord when he called to their house on the Costa del Sol, and is providing consular assistance.
The woman, who was in her 50s, and her daughter, were found dead in an upstairs bedroom of their apartment. Her husband was found dead downstairs.
Police in Spain say the owner of the rented villa had not heard from the couple for a number of days, causing him to call on the family.
Mijas is located on Spain's southern coast
It is understood that a note left at the house said the daughter's disability had become too much and had pushed the family to the edge. It is thought the note was written by Philip Wood.
The Wood family are understood to have been living in the area for several years.
Speaking on Wednesday evening after the bodies were found, a Guardia Civil spokeswoman said the family were renting the property where they were found dead. "The latest information we have is that the owner of the house had not heard from the family for a few days and had not been paid," she said.
"He went to the house today and when there was no reply at the door, he went inside. Inside he saw the man dead on the sofa and immediately called the Guardia Civil.
"When officers inspected the house they found the wife and the daughter dead in a bedroom. The initial hypothesis at this early stage of the investigation is that this was a murder-suicide."
The spokeswoman said she could not confirm reports that the daughter had Down's Syndrome.
Mijas is a popular town with a reputation for being family friendly with its many cafes and restaurants.