It appears that the woman accidentally strangled herself with the flex of a television at the psychiatric hospital in Co Cork.
The woman, believed to be in her 70s and originally from the north Cork area, was found by staff at St Stephen’s Hospital at Sarsfield’s Court in Glanmire last Sunday.
She was treated at the scene by hospital staff before an ambulance arrived and rushed her to Cork University Hospital (CUH).
The woman died the following day.
Gardaí were alerted and interviewed staff who were on duty at St Stephen’s at the time.
A Garda spokesman said the postmortem was carried out at CUH by Assistant State Pathologist Dr Margaret Bolster.
Gardaí are preparing a file for an inquest.
Meanwhile, the HSE is continuing to carry out its own investigation and has reported the incident to the Mental Health Commission.
The dead woman’s name has not been released by either the gardaí or the HSE.
St Stephen’s Hospital is one of the largest psychiatric units in the south of the country.
It caters for about 120 patients who are mainly in long-stay psycho-geriatric wards.
The hospital also deals with a number of younger people who experience temporary mental health problems.