A woman was found with serious head injuries in Mansfield by police investigating a man's death nearby.
The body of a 59-year-old local man was found near the car park at the Four Seasons Centre on Tuesday afternoon.
While informing relatives, police discovered the 58-year-old woman at a house in Victoria Street. She is in a critical condition in hospital.
The man's death is not being treated as suspicious, said a spokesman for the Nottinghamshire force.
Officers are still trying to establish the exact nature of the pair's relationship.
The injured woman underwent emergency surgery at the Queen's Medical Centre on Wednesday morning.
The house on Victoria Street has been cordoned off and forensic officers are at the scene.
Police said they were not looking for anyone else in connection with the incident.