Postmortem examinations are expected to be carried out on Thursday on the bodies of a brother and sister found at their home in Galway's Westside on Wednesday.
They were in their fifties and living in the house in Coogan Park, Newcastle.
Gardaí at Mill Street station said they were not treating the deaths as suspicious, pending the postmortems and further examination of the scene.
The alarm was raised when neighbours reported they had not seen either of the siblings in some days.
The bodies were discovered shortly before lunchtime and identified by a family member.
It is understood there was no sign of a break-in, and there was no indication that either sibling had sustained injuries.
Gardaí are understood to be pursuing a number of lines of inquiry, including the possibility of carbon monoxide poisoning or substance overdose.
Neighbours expressed shock and upset as the bodies were removed to University Hospital Galway for post-mortem examinations. The house was sealed off for forensic examination.
The woman had spoken late last year of moving to stay with family in England. Her brother lost his daughter about a year ago, and friends said he had never recovered.
A close friend who runs a dog training and minding business in Bushypark said she had known the woman for some years.
“She was a dear friend, and it was always nice to see her,” she said.
“I am absolutely devastated and my sincere sympathies are with the family.”
