The 20-year-old son of a man who died after being stabbed in the leg was still being questioned by gardai last night.
Marcus 'Murt' Brennan (46) died after the incident at a house on Frederick Avenue in Carlow town at around 1.30pm yesterday.
It is understood a number of people were in the house when he was involved in a heated argument before the stabbing took place.
His son, Marcus Hannon, who works as a kitchen porter in a local hotel, was arrested at the scene.
"This is a very tragic incident. What happened here happened in the heat of the moment," a source told the Herald.
Sources said that toxicology reports will be crucial in determining how the investigation proceeds.
While Brennan had numerous convictions and was very well-known to gardai, sources said the dead man was "not the worst of them".
"This unfortunate man was no criminal mastermind. He was in trouble for most of his adult life but all his problems related to his drug addiction," a source said.
Brennan had served a number of prison sentences, including a three-year stretch handed down at Kilkenny Circuit Court in February 2005 for stealing more than €6,000 while armed with a hammer at an EBS in Kilkenny.
He was also previously given a four-year sentence for robbery at Naas Circuit Court and was serving a separate three-and-a-half-year term for robbery in 1998.
He later launched a High Court challenge to the legality of his detention at Portlaoise Prison because of what he claimed were degrading conditions there. In recent times he had been involved in a low-level dispute with other criminal elements in Carlow.
He was due before the courts again in March, when he was to face charges of possession of a knife, criminal damage and burglary.
Forensic investigators were searching the scene last night in order to piece together the events leading up to the stabbing. A team of gardai were also conducting door-to-door interviews.
Neighbours said they were shaken by the incident.
"It's very frightening," said Rocio Thompson, who lives two doors from where the incident happened. "I have young children and I didn't know what to do."