Gardaí believe a man who burned to death in a well-known period house may have been assaulted before the fire was started deliberately.
A 38-year-old man with an address in the Coolock area of north Dublin was being questioned last night about the death after he presented himself to gardaí in Raheny.
Dublin Fire Brigade was alerted to the fire at Redcourt House, Seafield Road East, in Clontarf, Dublin 3, shortly after 2.30am yesterday.
The fire was brought under control by five units of the brigade but the property was destroyed. The unoccupied house is a late-Victorian property, dating back to the 1890s, on 1.65 acres.
It was sold to the developer Mark Piggott in 2004 for €7.5 million, €3.3 million more than its guide price. The site is now estimated to be worth in the region of €12 million.
A man believed to have been in the house before the fire broke out presented himself at Raheny Garda station as the fire was still burning.
Gardaí subsequently contacted Dublin Fire Brigade just after 4.15am to inform it a body may have been in the building. Following a search, the victim's remains were found.
The scene was sealed off by gardaí and the inquiry was upgraded from an investigation of arson to one of murder.
The man who presented himself at Raheny was arrested under Section 4 of the Criminal Justice Act. He was detained and remained in Garda custody last night.
He can be held for 24 hours without charge. It was expected a criminal charge would be put to him at Raheny Garda station last night, ahead of a court appearance this morning.
Gardaí believe the arrested man, the deceased and at least one other person were drinking in the house late on Wednesday night and into the early hours of yesterday morning.
They are working on the theory that an altercation took place during which the dead man was assaulted and after which the fire was started.
His remains were badly burned and it is believed a formal identification may take some time. A postmortem was begun yesterday.
The substantial Victorian property destroyed in the fire has been at the centre of a protracted planning dispute in recent years.
An original proposal to demolish the house and build 54 apartments was rejected by both Dublin City Council and An Bord Pleanála.
Although the developer succeeded in stopping the house being listed as a protected structure, An Bord Pleanála said it was an "intrinsic element" of the site.
However, a proposal earlier this year to retain the house as part of a new scheme involving 37 apartments and nine townhouses was given planning permission by Dublin City Council. It would have involved converting the house into four separate apartments.
It is now the subject of an appeal to An Bord Pleanála by local residents who maintain the house would be "completely overshadowed and dwarfed" by the apartment block which would be built in the grounds.