A mum-of-three was being questioned last night following the death of a 39-year-old man who was stabbed a number of times as he tried to start his car in south Dublin.
Gardai are not looking for anyone else in relation to the death of Gareth Kelly, who is originally from Donomore Park in the Killinarden area of Tallaght.
Detectives are investigating whether he was stabbed in a row over a parking space.
A 38-year-old woman, who was being detained in Clondalkin Garda Station last night, was arrested shortly after the 7am knife attack in the Brownsbarn Estate in Kingswood.
Sources said she was psychologically and medically assessed and was in a distressed condition when detained.
Mr Kelly is understood to have been stabbed at least three times after being attacked when he tried to start the car in a parking space that may not have been his.
It is understood he had left his partner's home to go to work but the car would not start.
He was trying to jump-start it when he was attacked.
The woman who was arrested lives in a nearby house, which was the subject of a major garda search operation yesterday.
Mr Kelly and the woman were not known to each other, nor were they known to gardai for involvement in criminality.
Mr Kelly's Skoda, which had the bonnet open and jump-leads attached to the battery, was examined at the scene before being removed for further investigation.
People living in the estate expressed their shock at what had happened.
One woman, who did not want to be named, said her daughter was "very shaken up".
"She's doing her best to help the guards in any way she can, but we can't get inside her house to see her," she said.
"She lives close to where the incident happened, so maybe she has information that can help them."
Another woman told the Herald she used to live in the house that was being inspected by gardai and forensic officers.
"I moved out of there about four years ago. I nearly fainted when I heard what had happened," she said.
"I'm just so shocked that something so violent happened right outside my old house.
"It's an awful tragedy, and hopefully the person responsible is brought to justice."
Another resident described Brownsbarn Wood as "a very respectable and quiet place to live".
"I woke up to the sounds of guards knocking on my door to question me whether I had seen or heard anything," he said.
"I'm not sure what happened, but it was an awful thing to hear first thing in the morning.
"The residents who live here usually leave for work or college quite early, so I'm sure someone is in a position to help the guards."
Gardai continued to assess the scene and conduct door-to-door enquiries throughout the afternoon.
The victim's body was examined at the scene by the pathologist before being removed by ambulance.
Gardai have launched a murder investigation and appealed for information.
"An Garda Siochana are investigating all the circumstances surrounding the fatal stabbing as there is no known motive at this time," a spokeswoman said.
She added that gardai are appealing to anyone who was in the Brownsbarn Estate and Kingswood area between 6am and 7am yesterday to contact them.