A third man has been arrested in relation to the fatal assault of Tommy Dooley, who was attacked at a funeral in Tralee on Wednesday.
Gardai arrested the man, aged in his 40s, on Monday evening.
He is currently detained under Section 4 of the Criminal Justice Act, 1984 at Tralee Garda Station.
A garda spokesperson said: "The local investigation team has been assisted by specialist investigators attached to the GNBCI."
The news comes after Patrick Dooley was charged with the murder of his brother Tommy on Friday.
The 35-year-old appeared at Kenmare District Court in Kerry on Friday morning.
Tommy Dooley, 40s, was stabbed to death while attending the funeral of a friend , while his wife Siobhan, 40s, also sustained serious injuries.
The couple, from Killarney, were in Tralee's Rathass Cemetery for the interring of family friend Bridget O'Brien, who died suddenly on Sunday, following requiem mass when they were both attacked and stabbed at around 11.45am.
Ambulance personnel pronounced Mr Dooley dead at the scene, and his body was taken to University Hospital Kerry.
Detective Garda Mark O'Sullivan of Tralee Garda Station said Patrick Dooley had been charged with his brother's murder at 5.03 on Friday.
The Detective Sergeant said that when the charge was put to him, Patrick Dooley replied: "I didn't harm my brother at all in any way. That is all I have to say."
Patrick Dooley, a married father of one, was remanded in custody to appear in court again this week as the District Court does not have the power to deal with issues of bail for a murder charge.
Judge Waters remanded Patrick Dooley to appear again before Tralee District Court by video-link on Wednesday.
Dooley was granted free legal aid defence solicitor Padraig O'Connell told the court that he was a carer for his wife and child.
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