The Garda are continuing to search for clues to the death of men in counties Clare and Waterford.
Gardaí are not saying if they are treating either killing as murder until after the results of post-mortems expected later today.
A man was released today in the investigation into the fatal stabbing of Mr Gary Doyle (28), who was killed in the early hours of New Year's Day.
Mr Doyle, a single father-of-one, was walking with his partner and a group near his home in Ballybeg, when he apparently became involved in an altercation shortly before 3 a.m. He was stabbed in the neck and died later in hospital.
The man detained by Garda overnight in connection with the death was today released. He is from the Ballybeg area. A file is being prepared for the Director of Public Prosecutions.
The Garda said its investigation is ongoing and are appealing to hackney and taxi drivers who were in the Ballybeg Drive and Priory Lawn area between 1 a.m. and 3.30 a.m. on the night of the killing to come forward.
In Co Clare, police are investigating the death of Mr Seán Poland (39), who was reportedly shot late on New Year's Eve in his Ardnacrucsha home.
Mr Poland was shot after he opened the front door of his home to a group of men. His wife was then tied up and a sum of money was taken.
Gardaí believe the motive for the killing was robbery and are searching for a group of four to six men.