A 62 year-old woman has been found dead in a house in the Rhymney Valley and a man is in critical condition in hospital.
Gwent Police say officers were called to the home Davies Street, Hengoed near Ystrad Mynach at 0800 this morning after a call was made reporting two people had been found unconscious.
The woman was pronounced dead at the scene and a 63 year-old man was taken to Prince Charles Hospital in Merthyr.
Carbon monoxide poisoning is suspected but police are awaiting further tests.
The incident is not being treated as suspicious.
Police are trying to trace the family of a Caerphilly woman who died at Prince Charles Hospital on January 21st.
Wendy Humphries, who was 44 years old, lived in Chapel Terrace in the village of Hengoed.