The body of John Henry Sabine, who would now have been 85, was found at the rear of flats at Trem-y-Cwm, Beddau, on 24 November.
Det Ch Insp Gareth Morgan told the hearing in Aberdare there is an ongoing murder investigation.
Mr Sabine's wife Leigh Anne is the main suspect.
Mrs Sabine died of cancer on 30 October.
The court heard that a postmortem carried out by pathologist Richard Jones found the cause of death was blunt force trauma to the head, although the date of his death was unknown.
Coroner Andrew Barkley adjourned the case ahead of a pre-inquest review on 10 March.
A man found in plastic wrapping in the garden of his former Rhondda Cynon Taff home died of "blunt force trauma to the head", a coroner's court has heard.