Later, after they'd killed and chopped up the Kenyan, they boarded a bus to Tallaght, mingling with the hundreds commuting to and from jobs in a booming economy. One of the sisters, Linda or Charlotte, was carrying the Kenyan's head in a black bag as the bus ground and swayed through the heaving traffic.

Out in Tallaght, they carried the head through The Square, the first of the super retail centres designed to breathe life into a sprawling community. They walked to Sean Walsh Park where they buried the head. And then, when the demons wouldn't leave Linda alone, she went back and dug it up, brought it to another field in her son's schoolbag, sat on a bench drinking vodka and apologised to the severed head. "It should have been me Ma, not you, " she said to the head.

The physical contours of the story of the death and dismemberment of Farah Swaleh Noor will be familiar to anybody with a knowledge of the bustling capital. It ranges across the city centre, out into the suburbs, unfolding, not in some darkened lane or field, but before the eyes of the city's unsuspecting populace. It isn't a tale of gangland, where fear and violence are weapons, greed and survival the motivation. It's a window into an underclass who live in an invisible country with its own mores and which exists beyond the ken of most citizens.

Farah Swaleh Noor was a sexual predator who showed no compunction in employing violence to get his way with women. He arrived in the country claiming asylum, alleging that he had witnessed his family being murdered in Somalia. In truth, he was a Kenyan who previously worked as a fisherman off the coast of east Africa and came here seeking a better life, or running from a former one. His deception wasn't unusual, or serious, but his character was horribly flawed.

One day, in Dr Quirkey's Goodtime Emporium on O'Connell Street, he eyed a young Chinese girl playing pool. She was a person with special needs, with the mental age of a child. Noor asked her back to his apartment, where "he tried to do something on me. He tried to do something, make sex with me, " the woman told the Central Criminal Court. The woman got pregnant following the encounter, and gave birth to a boy.

Noor fathered another child with a girlfriend, who told the court that he raped her on an almost daily basis. She said the 38-year-old Kenyan was a "lovely man" at first, but when he had drink taken, he changed. He also engaged in self-harm, often burning himself with cigarettes. On one occasion the woman returned home and thought he had burnt her son in a similar manner, but the hospital didn't confirm the injury. She feared for her life and got a barring order against Noor.

From there, Noor began a relationship with Kathleen Mulhall, a mother of six from Kilclare Gardens in Tallaght. She left her husband John, a man who was employed locally and well regarded. John stayed in the family home with his youngest son and three daughters, the eldest of whom, 30-year-old Linda, was herself a mother of four.

Kathleen moved into an apartment in Richmond Cottages in Ballybough in the north inner city. She kept in sporadic contact with her family.

The couple moved to Cork in 2003. Their relationship was violent. Mulhall was admitted to hospital a number of times with bruising and blurred vision. Back in Dublin, the pattern continued. Mulhall sought advice from Noor's previous partner, who had experienced similar violence. The woman told Mulhall to leave him.

Early in March 2005, Mulhall alleged that Noor had threatened to kill her, cut her up and put her in a fridge, and then he would eat her, bit by bit. On 20 March, the couple were in the city centre and were joined by two of Mulhall's daughters, Linda and 22-year-old Charlotte.

Sometime after 5pm, a friend of Noor's, Abu Bakaar, met them on O'Connell Street. Noor was wearing the white Irish football strip, and he appeared to be arguing with the women.

"I can't talk to him because I know after a few drinks, Farah, anything can happen to him, " Bakaar told the court.

They bought vodka in one shop and coke in another, and began tippling on the street. On the boardwalk, the three women took an ecstasy tablet each. Later, Kathleen Mulhall crushed another tab and put it into Noor's vodka and coke, because, according to her daughters, she wanted the man to experience the same buzz they were on.

On the way back to Mulhall's apartment, Noor pointed out a Chinese boy whom he said was his son. Another row flared up.

Sometime later that night, 38-year-old Noor was violently assaulted and killed. Statements from the sisters claim he made advances to Linda and wouldn't back off. In one version, Charlotte claimed that, during the ensuing row, their mother begged her daughters to kill her lover. "Please, just kill him for me, " Charlotte alleged her mother said.

Both agree that Charlotte attacked the Kenyan with a Stanley knife, slashing at his throat, but those wounds were not fatal. He stumbled towards the bedroom. Charlotte stabbed him.

She doesn't remember how many times. His body had 22 stab wounds. Linda hit him repeatedly on the head with a hammer.

Afterwards, they dragged him into the bathroom and began cutting him up. Charlotte sat on the toilet seat, sawing the body with a knife.

Linda was in the shower, swinging a hammer to break bones. "The smell, it wouldn't go away. I think about it every night, " Linda told the gardai.

On the occasions that the night was brought back to life during the trial at the Central Criminal Court, Linda bowed her head, and kept it buried behind her long blonde hair, as her body heaved to the rhythm of sobs. Charlotte remained more composed, but broke down a few times.

At some point on the morning of 21 March . . .

Charlotte's birthday . . . or over the following days, the body was taken in bags to the Royal Canal and dumped in the water. The man's head was kept at the apartment until its journey to Tallaght. The man's penis was never recovered, a detail that prosecuting counsel invited the jury to consider.

It isn't clear how long the extensive clean-up took. A forensic examination months later uncovered blood in the grooves of the wooden floorboards. At one stage the three women went to a local shop to buy more bleach. There is a suspicion that the girls' father, John Mulhall, showed up at some stage . . . possibly days after the killing . . . and helped with the clean-up.

The investigation was going nowhere until the intervention of Noor's old friend, Baaker, who read in Metro Eireann about the search for the identity of the dismembered body in bags, which also included an Ireland away strip. He remembered the day in O'Connell Street.

The three women fled for a while to Manchester. On 3 August, they were arrested and interviewed along with John Mulhall. Two weeks later, Linda cracked, and rang Inspector Christy Mangan wanting to talk. When Mangan called again, she was ironing her children's clothes. She related that her daughter was showing great potential at athletics.

For a while, soon after the murder, her two sons had to do without schoolbags, because Linda and Charlotte borrowed them to transfer the head, although on that occasion, they eventually left it be. Later, Linda came back and dug it up and moved it herself. After she gave her statement to Mangan, she hugged the detective inspector.

Charlotte eventually came clean after being arrested on 19 October. Both were charged with murder.

Just before Christmas last year, John Mulhall succumbed to whatever demons had been released by the actions of his wife and daughters.

All that he knew, and all that would be revealed, must have been too much to bear. He went to the Phoenix Park, threw a rope around a tree and hanged himself. Soon after, his wife left the jurisdiction. She is believed to be living in London.

Earlier this summer, Charlotte gave birth to her first child while out on bail. Her bail was revoked when she broke the conditions. Linda failed to show up for the scheduled trial due to falling into heroin addiction. The court heard from a psychiatrist that she was also drinking three bottles of vodka a day, and had engaged in self-harm on a number of occasions. The five children from the two sisters have been visiting their mothers in the women's prison in Mountjoy since they were taken into custody.

Yesterday, on the fourth day of deliberation, a verdict was finally returned. None of the dead man's family was in court, although his friend Baaker did sit in on some of the evidence. The sisters' elder brothers and their younger sister, an apprentice mechanic who gave evidence for the prosecution, were in court at various stages throughout the trial.

A file on Kathleen Mulhall's involvement on the fateful night is with the DPP. The director may yet decide to prosecute her. Gardai are understood to know her whereabouts in London.

When the body parts were found on 30 March last year, at first there was fevered speculation that a ritual killing had occurred. The dead man was black, most likely African. They do things differently there. Primal instincts surrounding the basic treatment of human remains are observed in prosperous, western society. There couldn't be an indigenous angle.

There was. It was plucked from the ranks of the new underclass, people wholly disconnected from the advances made over the past decade, many of them damaged irreparably before adulthood. It was in such a moral vacuum that Farah Swaleh Noor, a violent man, met his violent end, and his remains were defiled and dumped in the Royal Canal.