Detectives are investigating if a pensioner was murdered during a burglary at her home before being left undiscovered for almost a week.
The victim has been named locally as Ann Butler (70), who lived alone at Maudlin Street in Kilkenny city.
A man in his late 20s was last night being quizzed by gardai on suspicion of her murder.
The Herald has learnt that the suspect, who is from Kilkenny, alerted officers himself to the scene on Wednesday evening.
He brought gardai to Ms Butler's home and when they made the gruesome discovery they arrested him at the scene.
Searches at three other locations have also been carried out as part of the investigation.
Detectives are trying to establish the circumstances surrounding Ms Butler's murder and one line of inquiry is that she was killed in the course of a burglary.
A post-mortem was being carried out at a Dublin mortuary yesterday evening.
A source told the Herald: "The suspect is known to gardai but has not come to attention for any serious offences. He would be a petty criminal.
"There is no known connection between this individual and the deceased, and one avenue is that this was a burglary that went wrong."
Locals reacted with shock that such a vulnerable and elderly person could be found dead in suspicious circumstances.
Yesterday morning the scene remained sealed off, with garda tape stretched across the front of the small house in Maudlin Street in the north of the city close to the River Nore.
It is one of three houses grouped together and accessed by a small flight of steps.
Two gardai were on duty outside and Ms Butler's body remained in the house.
Members of the Garda Technical Bureau then arrived and carried out a forensic examination of the scene inside and outside.
Then just before 1pm a hearse arrived and Ms Butler's body was removed to the morgue.
Locals described the pensioner as independent but vulnerable.
She was often seen in the town but had not been spotted out since the weekend.
Neighbours became aware that something was wrong late on Wednesday evening when gardai, who appeared to have been acting on information, began calling to houses on the narrow street.
"It seems they had some limited information and were working on that," said one local man.
"They were knocking on doors and asking people about neighbours, and somebody must have said that Ann had not been seen.
"We haven't seen her since the weekend anyway, so it is possible she was there that long.
"Then the gardai went into the house and it was sealed off."
Local woman Jill Kavanagh brought flowers to the scene and gave them to a garda who then brought them down the small avenue to Ms Butler's house.
"This is a tight-knit community and we all look out for one another. We all know each other by name," she said.
"I'm shocked that this could happen on this street with its lovely people and lovely history.
"You would often see Ann out and about, and everyone around here knew her. People looked out for her because she didn't have it easy."
Another woman who lives locally said Ms Butler had her troubles in the past and that there should have been better systems in place to care for her.
"The system failed Ann, in my view. Somebody owed her a duty of care and it just didn't happen," she said.
"I've been on to the gardai several times out of concern, and now this is the situation we are in."
A Garda spokesman said officers were investigating "the circumstances surrounding the unexplained death" and added that a man was in custody on suspicion of murder.
The suspect is being held under Section 4 of the Criminal Justice Act at Kilkenny Garda Station.
Gardai are appealing for anyone with information in relation to the incident to contact Kilkenny Garda Station on 056 7775000, the Garda Confidential Line on 1800 666 111, or any garda station.