Post-mortem examinations today are expected to confirm that elderly couple Tom and Kitty Fitzgerald were killed on Tuesday as a result of murder-suicide at their home near Irishtown, Co Mayo.
The Office of the State Pathologist will begin post-mortem examinations in the early afternoon with preliminary results expected some hours later.
Mr Fitzgerald (75) and his wife Kitty (72) were found dead after an assault using a bludgeoning weapon at their home on Tuesday afternoon.
Their son Paul (37) was rushed to hospital in Galway with serious head injuries and has since been taken to Beaumont Hospital for further treatment.
It is understood that Kitty was found lying in a pool of blood inside the house, while Tom was found lying dead in a trough outside. A blunt instrument, apparently a metal bar, is being examined by gardaí to find out whether it was used during the assault.
The alarm was raised by a friend of the family who called to the Fitzgerald home shortly after 3 pm on Tuesday and came upon a scene of carnage.
Chief Superintendent Pat Diskin said an operation room had been set up at Claremorris garda station and a full team of investigators was in place.
"While this is a very serious incident, and is being fully investigated I'll be satisfied that the answers to our inquiries lie within the location of the incident," he said. "A full team from the technical bureau carried out a full examination. We have a full incident room set up - we're at the very early stages of the investigation and our various teams are doing serious work in relation to this matter and we're obviously trying to establish the full facts surrounding the tragedy."
Chief Supt Diskin said a much clearer picture of what exactly happened at the house would become apparent to investigators when State Pathologist Marie Cassidy conducted post-mortem examinations today.
"When the post-mortems are completed, it will certainly give us an indication into what direction the investigation will take," he added.
Chief Supt Diskin said the situation came to the Garda's attention at around 3pm on Tuesday. However, officers are still unsure of the exact time frame of the incident.
Investigating officers are asking anyone that may have seen anything suspicious around the property between Sunday night and Tuesday afternoon to get in touch with them.
Forensic scientists from the Garda's regional crime scene investigation unit arrived on scene at the house in Knockadoon, just outside the village of Irishtown, shortly after 11am yesterday.
A full inspection was carried out of the scene before they departed again at around 12.30pm.
Family members, including Tom's brothers Vincent and Frank, arrived at the scene but, with Garda tape stopping anyone from approaching within 300 metres of the house, they could not get close.
The bodies of the two victims were carried from the home at around 2.30pm yesterday.
The hearse was followed for up to 500 metres by a number of close relatives, and some neighbours and family friends who wished to pay their respects to the couple.
Before Mr Fitzgerald's body was removed to Mayo University Hospital, parish priest Father Martin O'Connor led prayers with family at the home.
His wife's body was removed from the scene shortly after.
The state pathologist is due to carry out post-mortems on the bodies in Mayo this morning.
Tributes have poured in for the tragic couple over the past 24 hours, with friends of the family and Fr O'Connor speaking of their shock. They said the well-known couple would be a huge loss to the community.
A community group met last night to help put together plans for the coming days and for the funeral, which is expected to be very large.
However, funeral details have not been organised and are not expected until this evening at the earliest.
Joe Reapy, of the local Davitts GAA club, said: "Tom had a great spirit when it came to community matters. If anything was going on, Tom was sure to have a hand in it.
"It's shocking, hard to believe this lovely couple are gone."
Tom played with Davitts during the 1950s, 1960s and 1970s and was involved as a member long after that. The club was due to hold a meeting on Tuesday night, but it was cancelled as a mark of respect.
Gardai are investigating after the bodies of an elderly married couple were discovered in their home while their son was found nearby with head injuries.