sundayworld.com understands post mortem results have led now gardaí to rule out the possible of a murder-suicide.
Officers are now satisfied that Nicholas Smith (81) died from natural causes.
However, medical attempts to clarify the circumstances of his wife’s death have so far provided inconclusive results.
It is believed the bodies of Mr Smith and Hillary (79) may have lain undiscovered in their Tipperary home for 18 months.
The case has puzzled locals in the rural area of Cloneen, between Fethard and Mullinahone, as they believed the couple had moved abroad during the Covid pandemic.
As they try to unravel the mystery, gardaí have also been in contact with police in the UK to try find any relatives of the Smiths. To date they have not been able to identify a next of kin.
The Irish Independent reported today that a central element of the garda investigation is why the bodies of were found in different rooms of the bungalow.
Detectives stressed they were keeping an open mind about the double tragedy, with the nature of their investigation to be determined by the pathologist’s findings.
Post-mortem examinations conducted by State Pathologist Dr Linda Mulligan at University Hospital Waterford on Tuesday.
The breakthrough this evening in relation to the cause of Mr Smith's death means gardaí can close off a number of potential theories.
However, they must continue to try establish how Mrs Smith died.
The property was fully secured when gardaí called at 4pm on Monday amid welfare concerns for the couple.
Locals had been told before the pandemic that the couple would be relocating to France.
However, a man who lived nearby became increasingly concerned at the unkempt nature of the house – and the fact that the couple’s car was parked behind the bungalow and had not been moved for more than 12 months.
He was increasingly unconvinced by the story that the couple had left Ireland and were selling the property to some UK-based friends.
There was no sign of forced entry when gardaí arrived and no indication of any disturbance within the bungalow. A careful search of the property yielded no weapons or anything to indicate foul play.
The body of Mr Smith was discovered in the bedroom of the bungalow. However, the remains of his wife were found just up the hallway in the sitting room. Blinds were drawn in the rooms involved.
Detectives are examining a number of theories, ranging from whether the Covid-19 virus was somehow involved in the circumstances of the deaths or whether another medical cause may be responsible.
A source said particular attention was being paid to a number of prescription medications that had been found in the property. Both of the deceased had been dealing with a number of health issues ranging from arthritis to an auto-immune disorder.
Such is the painstaking nature of the garda investigation that even the chimney and boiler in the property are being checked to eliminate carbon-monoxide poisoning as a possible cause.
Mr and Ms Smith were originally from the UK but spent many years overseas in France, Ireland, Australia and New Zealand.
Mr Smith is understood to have worked in the cruise-line industry. The couple had no children.
They are understood to have briefly lived in Southampton and London but were based in Tipperary for the past eight years.
Garda technical experts are now examining all banking, phone and computer records in a bid to determine the final timeframe of activity by the Smiths.
Neighbours last saw the couple in late 2020. Publican and local Fine Gael county councillor Mark Fitzgerald said the couple were very polite but they were also reserved and appeared to want their privacy respected.
Another local said they kept to themselves, did their shopping in Clonmel and Carrick-on-Suir and attended cultural events in nearby Cahir.