Emergency services were called to an address in Watermill Lane, Bexhill, at 1.45am on Saturday (6 February) after concern for a woman in the property.
The woman aged in her 70s was sadly found dead and a man known to her, also aged in his 70s, was found with significant injuries. He was arrested in connection with the incident and taken to hospital in a serious condition.
Police are working to establish the circumstances of the incident and officers will remain at the scene and in the area for the next few days during the investigation.
Detective Chief Inspector Chris Friday from the Surrey and Sussex Major Crime Unit said: “This is being treated as a tragic isolated incident and at this stage we are not looking for anyone else in connection to it.
“We are asking if anyone who has any information which could us with our investigation to contact us.”
Report online or ring 101 quoting Operation Woodhouse.