The body of a 29-year-old prison worker was found at HMP Isle of Wight’s Parkhurst site on Monday morning.
Hampshire Constabulary say they were called at 2:43am.
The death is not being treated as suspicious.
Support for prison staff
The director general of prisons told the BBC that following the death of a colleague, they were providing extra support to staff at HMP Isle of Wight.
He said his thoughts were with the family and friends at this difficult time.
A file has been passed to the coroner.
Source: BBC Hampshire
Image: Glen Carrie under CC BY 2.0