Gardaí believe that lonely pensioner Paddy Lyons may have invited his killer into his home.
Officers investigating his brutal murder think the 90-year-old victim may have known the killer from previous visits to his isolated house in Waterford. They are now trying to establish the circumstances that resulted in his vicious death last Friday night or Saturday morning.
A man in his 20s was arrested in the Tipperary area yesterday and brought to Dungarvan garda station for questioning in connection with the case.
Mr Lyons was attacked with a blunt weapon and suffered injuries to his head and face, resulting in broken bones. He also sustained injuries to his arms in what appeared to have been an attempt to shield himself from further blows to his head.
Mr Lyons, a bachelor and an only child, lived alone in the rural townland of Loughreagh, Ballysaggart, 11km from Lismore, Co Waterford. Every Friday, he organised a lift with either a neighbour or a carer to Lismore to collect his pension. He was last seen on Friday evening, according to gardaí.
Officers believe that Mr Lyons had befriended several groups of people who lived outside the area but called regularly to visit him.
They suspect that a number of people may have visited the house later on Friday and were allowed in by Mr Lyons.
At some stage during the night, some of the visitors started an argument with Mr Lyons, who was then subjected to a sustained attack.
The weapon used in the assault has not yet been identified but gardaí carried out a detailed search of the house and surrounding land yesterday. Officers were also attempting to determine if anything had been stolen from his home.
Earlier yesterday, gardaí issued an appeal to a man and woman, who had alerted a neighbour to the tragedy and then driven off in a van, to come forward. Officers said later that the couple had made contact and had been eliminated from their inquiries. Shortly after 5pm yesterday, officers arrested a man in his 20s in the Tipperary area. He was being held last night under section 4 of the Criminal Justice Act, 1984, which allows gardaí to detain him without charge for up to 24 hours.
Mr Lyons was known to have operated an "open house" for visitors, ranging from those he knew well from the area and others who had built up a friendship with him. The pensioner was targeted in a burglary in 2011, when the burglars disguised themselves as gardaí.
Neighbours said Mr Lyons was an outgoing type, who enjoyed chatting with callers and was vulnerable to those who would take advantage of his good nature. Security was lax at the house, which made it a potential target for a break-in, they said.
In recent years, a number of locals in the Ballysaggart community had operated on a rota system to keep an eye on Mr Lyons.
There was concern for his well-being when he didn't appear at the funeral of a woman in the parish on Saturday morning. The lady was a close friend whose son is understood to have provided lifts to Mr Lyons in recent years.
Signs for Community Watch are located at the entrances to the village and Tom Veale, treasurer for the group and a friend of Mr Lyons, explained that Mr Lyons had been offered an alarm system but decided against it. "It has caused a lot of shock. He was well able to get around, and he was very alert," Mr Veale said.
Gardaí said last night they had not yet recovered the weapon used in the murder but were checking items for a forensic examination. Mr Lyons' home is situated more than half a kilometre away from his nearest neighbours - with the hamlet of Ballysaggart consisting of only a church, pub and two shops.
Lismore is the local garda station for Ballysaggart - and is within 10km. However, the station's opening hours are only between 10am and 1pm, Monday to Friday.