A postmortem carried out yesterday on the bodies of Ella Butler, 2, and her sister, Zoe, 6, concluded both died of asphyxiation.
The body of their father, John Butler, had to be identified through dental records.
His remains were severely burnt after he deliberately crashed his car into a ditch around a mile from the family home in Ballycotton on Tuesday morning.
The postmortem examination showed he died of smoke inhalation.
It is believed Mr Butler, an unemployed builder, killed his daughters shortly after his wife, Una, left for work at 7.30am.
He was on his own in his Toyota Yaris when he went to the local petrol station at 9.20am that day.
Mr Butler purchased €20 worth of petrol which he put in a container. It is believed he doused the car with petrol before driving it into a ditch. It burst into a fireball on impact.
Meanwhile, it emerged that a 31-year-old man arrested in Co Clare in connection with the deaths of two children and two adults booked into a hotel in Kilkee on Monday night. It is understood the suspect had given up the idea of going on the run and called a retired garda from a public phone in the west Clare resort on Tuesday in the wake of a drinking binge. The message he left led gardaí to the murder scene in a house in Hazel Grove, Newcastle West, Co Limerick, where they found the bodies of Sarah Hines, 25, her two children Reece, 3, and Amy, 5 months, and her close friend Alicia Brough, 20.
The suspect was tracked to a pub in Kilkee and arrested on Tuesday afternoon. Gardaí believe the murders were carried out late on Sunday night or some time on Monday.
The quadruple murder suspect, who hails from Milford, north Cork, was being held at Henry Street Garda Station in Limerick city overnight but was brought to Cork University Hospital for treatment to his hand.
Ms Hines’ stepfather Peter Rolph, from Tournafulla, Co Limerick, said her mother, Abina, and seven brothers and step-brothers were completely devastated at their loss. “Nothing will ever be the same,” he said.