A 75-year-old man was arrested on suspicion of murder after the woman died on Christmas Eve.
Police in North Wales said the officers were called to a home in Fairbourne, Gwynedd, immediately after reports at 20.00 on Wednesday reported that a 74-year-old woman suffered serious injuries.
Despite the efforts of the family of women, police officers and rescuers, she was declared dead at the crime scene, a spokeswoman for the armed forces said.
DCI Brian Kearney said: “After a police presence at Francis Avenue, Fairbourne, Gwynedd, a 75-year-old man was arrested last night for suspected murder and is currently in custody at a local police station.
“The Coroner for Northwest Wales, Mr. Dewi Pritchard Jones, was informed.
“This is indeed a tragic and very rare occurrence in Northwest Wales, and I would like to assure the public that we are not looking for anyone else in relation to this event.
“A large incident room was set up at Caernarfon Police Station.
“Family liaison officers support the victim’s family and our thoughts remain with them. I would ask that their privacy be respected at the moment. “