THE 20-year-old female suspect – who is also a member of the Travelling community – handed herself into Blanchardstown Garda Station voluntarily yesterday.
After a period of questioning gardai decided to arrest her.
Senior sources are working on the theory that Ms Cash received fatal brain injuries after being kicked a number of times in the head.
"The dispute escalated to the point where Ms Cash received a number of kicks to the head which led to her death," a source said.
Three other people who were voluntarily questioned over the incident were released from Blanchardstown Garda Station last night and gardai are not looking for anyone else in relation to the murder.
Ms Cash is originally from Greystones, Co Wicklow, while the suspect is a homeless woman originally from Blanchardstown who is known to gardai.
It has emerged that after Ms Cash was assaulted at the house in the early hours of yesterday morning, a number of people who were in the property left the scene.
However at least three of those people returned to the house at around 10.30am yesterday and alerted the emergency services that Ms Cash was dead.
Throughout yesterday, they helped gardai with their detailed enquiries before being released last night.
The murder victim, Brigid 'Bernie' Cash, had also suffered a brutal attack in the weeks before her violent death, her mother told the Herald.
The mum-of-one had been savagely scalded and beaten in a brutal attack just weeks before she was killed.
Her body was found with head injuries in the living room of the house in Warrenstown Walk in Blanchardstown in Dublin at 10.40am yesterday.
She had been dead for several hours.
Her mother Brigid told the Herald: "She was terrified and was hiding out. I had spoken to her on the phone a few days ago but I was going to report her missing to the guards this morning."
She said her daughter was strikingly good looking. But a recent violent attack resulted in her suffering severe scalding all over her body, her ankle had been broken, and her two eyes had been heavily bruised.
"She was a beautiful, good looking girl that looked just like the actress Elizabeth Taylor. I used to brag about her all the time," her distraught mother said.
"I hope they find who killed her. We want justice."
Fighting back her tears, she said her daughter had been separated from her husband but the couple were on good terms and it was hoped one day they could get back together.
"Bernie lived for her little boy, Michael. He was all she wanted," she said.
The grieving mother broke down in tears several times as she spoke about her beautiful daughter.
She said that all her family always called her daughter Bernie although her official name was Brigid.
"She was named Brigid but we called her Bernie since the holy nuns in Kilmacud told us we should call her after Saint Bernadette," she said.
She spoke to the Herald at the home of her mother, Bernie's grandmother Brigid O'Brien (70) who lives in Mulhuddart.