An "accelerant " was used in the fire which led to the death of a man and severe injuries to another near Anascaul in west Kerry last week, according to gardai.
A post-mortem indicated that Mr John Herlihy (43) died of smoke inhalation when the living room of his bungalow at Kielduff was destroyed by fire.
Gardai are treating the case as a criminal investigation.
A lorry driver died yesterday when he was pinned between two vehicles in Ballaghaderreen, Co Roscommon.
The dead man was named last night as Mr Stephen Donnelly (33), from Farranattee, Caherdaniel, Co Kerry.
Gardai said that Mr Donnelly was trapped between two lorries during a towing operation.
