Police are investigating the death of a woman in her sixties at an address in Meare Green, near West Hatch, Taunton.
The ambulance service was called to the house in the early hours of Sunday 17 December after the woman was found unresponsive. She was pronounced dead and police attended.
The death was being treated as unexpected and the initial post-mortem results were inconclusive.
On Thursday 21 December new information was given to officers and an investigation is now being led by the Major Crime Investigation Team (MCIT) pending the outcome of a forensic post-mortem examination.
A man in his sixties, known to the woman, was arrested on Friday 22 December and remains in police custody.
“Our thoughts are with the woman’s family at this very difficult time” said Avon and Somerset Police.
“Residents will see an increased police presence in the area while forensic teams and specialist officers search the property and door-to-door enquiries are carried out.”
Detectives are keen to hear from anyone with any information, CCTV or other footage which could help with the investigation by calling 101 and giving the reference 5223311708.