A body found in a lake is believed to be that of a serving female police officer, Cheshire police said.
The body, which was found at about 03:45 BST at Poynton Park in Cheshire, is thought to be that of Leanne McKie, 39, from Greater Manchester Police.
She was the mother of three young children, Cheshire Constabulary said.
A 43-year-old man from Wilmslow man has been arrested on suspicion of murder and is being questioned by detectives.
Police said it appeared to be an “isolated incident”.
Det Insp Adam Waller said: “Investigations into her death are currently ongoing and we are working hard to establish the full circumstances surrounding the incident.
“We are aware of a number of rumours circulating in relation to the identity of the victim and, whilst formal identification has not year taken place, we do believe that the victim is 39-year-old Leanne McKie, from Wilmslow.
“Our thoughts at this difficult time are with Leanne’s family, friends and colleagues.”
He said police were not looking for anyone else in connection with her death.