Police are awaiting the results of a Home Office Post Mortem to determine the cause of the deaths of a mother and baby found on Wednesday afternoon in a house in Merthyr.
Detectives say they are, at this stage, treating the deaths as unexplained but believe they may have been dead for some time.
The mother and child have been named locally as 27-year-old Joanne Thomas and her four-month old daughter Harper.
They were discovered inside the property at Church Street in Troedyrhiw by police officers who entered the address after concerns were raised for their welfare.
Officers are continuing their appeal for information, and an incident room has been set up at Cardiff Central Police Station.
Joanne Thomas and her four-month-old baby Harper were found dead at their home in Merthyr Tydfil in July. An open verdict has been recorded.
Police add there is 'no evidence to date' to suggest carbon monoxide killed the two, believed to be a mother and her four-month-old baby.