A man was being questioned by gardaí last night after a body was found in a house on the capital's northside.
Gardaí are treating the case as murder after examinations showed that the 42-year-old victim had severe head injuries when his body was discovered in Phibsboro.
A man well known to the victim was arrested yesterday afternoon and questioned by detectives following the grim discovery.
"This is a very tragic case, both the victim and the arrested man were very well known to each other," a senior source said.
"The two men had not been getting on very well in recent times and there was a lot of arguments and tensions in the lead-up to this incident."
The arrested man is understood to be a couple of years older than the victim, who had been living in the Phibsboro area for decades.
Neither men were previously known to gardaí for involvement in crime.
Detectives are not looking for anyone else at present in connection with the violent death.
"Gardaí have arrested a man in relation to the discovery of a body of a man (40s) on Auburn Street, Dublin 7, on Friday afternoon," a garda spokesman said.
"The arrested male (40s) is currently detained in Mountjoy garda station under Section 4 of the Criminal Justice Act, 1984, on suspicion of murder.
"A technical examination of the scene is currently under way by the Garda Technical Bureau.
"The body of the man remains at the scene and the services of the State Pathologist have been requested.
"A garda family liaison officer has been appointed and is in contact with the family of the deceased.
"Investigating gardaí are appealing to anyone with any information on the death of this man to contact them at Mountjoy garda station at 01-6668600, the Garda Confidential line 1800 666 111 or any garda station."
Local councillor Anthony Flynn (Independent) said the incident has left the local community of Phibsboro and Broadstone shocked.
He said the victim and his family are well known in the area.
"I was in the area today. The Broadstone area is a quiet community and the family is very well known," he told the Herald last night.
"It's a tragic, tragic incident."
Fellow councillor Seamus McGratten (Sinn Fein) said he was also shocked to hear of the tragedy.
"It's a quiet settled area and this is very surprising to hear," he said.
"I appeal to anyone with information to come forward."