Two other children were also in the room. Anton Mulder looked up and saw Derek Halligan and June Maguire at the window. He took the child from his knee and went to open the door.

"She's upstairs, " he told the gardai. He appeared to be very upset. Through the door of the front room, Garda Maguire could hear a baby crying. Upstairs, Maguire found a woman lying on a double bed. Her body was warm, her eyes partially closed. There was bruising around her neck.

Within minutes, an ambulance crew attempted cardiopulmonary resuscitation manouvres to save the life of mother-of-six Colleen Mulder. There was no response. Downstairs, her husband was sobbing. The tensions, violence and recriminations that had punctuated life behind the family's closed doors had reached their nadir in the strangulation of Colleen Mulder on 17 December 2004.

Colleen was seven when her family emigrated to South Africa in 1970. Patricia Feriera and her husband considered the country a better prospect for their three children than Northern Ireland, which was exploding with the Troubles. They swapped Bangor, Co Down, for Durban in the Natal province.

Colleen was in her early 20s when she met Anton Mulder, an Afrikaaner native of Durban. The couple married in 1985. Mulder was well regarded by Colleen's family, and became quite friendly with his brother-in-law, William Carson Pollock, who was two years younger than Colleen.

A son, Clinton, was born soon after, quickly followed by Kristopher. The late '80s, however, were a time of upheaval in South Africa with a growing clamour for the end of apartheid.

Mulder feared the wind of change.

Years later, in Dublin, he would relate darkly how he was affiliated to one of the right-wing groups that opposed the handover of power to the ANC. "He said that he and two other fellas had gone to blow up a dam, but it didn't come off", said someone who knew him then. "After that he maintained he was effectively run out of the country." The source put the tale down to fantasy, but it was obvious that Mulder didn't see a future in his native country.

The Mulders relocated to Bangor in 1992. Colleen's own family, including her mother and brother, also came back.

In the North, three more daughters were born, Roxanne, Samantha and Saskia. Despite their growing brood, the marriage doesn't appear to have been happy.

There are conflicting accounts as to the prevalence or extent of violence.

Last week, Colleen's sister Ann said Mulder was regularly violent with Colleen. Their other sibling, William, agreed.

Yet none of the couple's offspring who gave evidence against their father ever saw him hit Colleen. Clinton . . . who told gardai, "My father used to treat us all like shit; he used to hit me until I was 15 or 16, when I could hit him back" . . . said he never saw Mulder hit Colleen or any of his sisters. Kristopher told the gardai that his father would "hit inanimate objects when he lost his temper", but he never saw him hit his mother.

Neither did Roxanne, although she did say they fought all the time.

Mulder himself told gardai he was never violent towards Colleen, but said she hit him on occasions. Among the items recovered from their home was a leaflet for the group Amen, which offers advice to male victims of domestic violence.

He also made references to barricading himself into a bedroom, and being in fear that Colleen's brother might come after him with an AK-47. He suggested that Colleen had threatened to acquire an AK-47 from William to shoot him. There was no evidence to indicate that these were other than the fantastic ravings in which Mulder sometimes indulged.

'Street angel, house devil' By 2002, Mulder had obtained a job as regional manager for Kentucky Fried Chicken. The new role required a move south. The family settled on Dunshaughlin, a half hour from Dublin. A sixth child, Shannon, was born after the family moved.

The fast food outlet was a major part of the Mulders' lives. Anton worked long hours overseeing all the group's branches, from Dublin to Belfast.

Colleen worked in the Blanchardstown branch two days a week, where Clinton and Kristopher were also employed.

Johan De Waal, who would befriend the family, and conduct an affair with Colleen in her final months, worked there part-time. The Mulders' nextdoor neighbours in Dunshaughlin, another Afrikaaner family, found jobs in KFC. And the Afrikaaner cook in the Blanchardstown KFC was a vital witness in the murder trial.

Mulder later told gardai that work was his only real interest outside his family. But a year or so after arriving in Dunshaughlin, he got involved in the Civil Service Cricket Club, based in the Phoenix Park.

The term "street angel, house devil" is often used for somebody showing one face to the world, another to family.

Whether or not Mulder conformed to that, he was certainly popular in the cricket club. On arrival, he claimed that he had kept wicket with Natal province back home, a position that would equate in status with playing rugby for Munster.

The boast appears to have been another strand in the parallel fantasy world Mulder sketched for himself. He found his level on the second team, but he wasn't slow to help out whenever called on to do so.

"He brought a lot of people into the club, Asians and Indians who were working in Kentucky Fried Chicken, " one club source remembered. "And he was often helping out. We had a summer barbecue and he showed up with bucket loads of fried chicken.

"He worked hard. He might have to go up to Belfast in the evening, leave there in the early morning, home at four or five and get up in the morning to play a game. We found him fine."

His contribution was recognised in 2004 when he was named "clubman of the year". After he was arrested, at least one club member offered to give character evidence if called on to do so.

In July 2004, Colleen suffered a miscarriage. The tragedy was a catalyst for much that followed. It was after a party in their home in September that Mulder realised that Colleen was having an affair with Johan de Waal. A truck driver, who had also worked for a spell in KFC, De Waal befriended the family after Anton lent him 6,000 to buy a car.

At the party, Mulder told De Waal that he was going to do a runner. "He said he had enough of his family, he was going to max out the credit cards, take a second mortgage out on the house and disappear to South Africa, so he could show his dad that he had made millions without his dad helping him, " according to De Waal.

A few days after the party, De Waal received a text from Mulder, telling him their friendship was over. "I said that I knew why [in a replying text], " De Waal told the court. He wouldn't describe his relationship with Colleen as an affair, but admitted that they had had sex at least twice.

Halloween rolled around to the Mulder home without much joy. Roxanne saw her mother slap her father a number of times after they rowed. Colleen told Anton to hit her back, but, their daughter remembers, he said he "wouldn't stoop that low". Within weeks, Colleen had moved out, returning to her mother's home in Bangor.

'I'm going to kill her' One evening in early December, Mulder called in next door to the Koortzens, another South African family. Chris Koortzen's wife and son both worked part-time in KFC. At one stage Mulder broke into the men's native tongue, and issued a threat that translates as: "I feel I can pick up a knife and make ends of her." Koortzen didn't take it seriously. He told Mulder to see a lawyer about his marital difficulties.

A week later, Mulder was chatting to Andries Loubser outside the KFC in Blanchardstown. "He said, 'I'm going to kill her. I'm going up North and go to the house and kill her, '" Loubser told the court. "He said it's easy in this country.

You only do five or six years; he'd still be a young man by the time he gets out of prison."

Within days, Colleen returned to Dunshaughlin, intending to stay over the Christmas period. By then, she had talked to a solicitor about getting custody of the children.

On the morning of 17 December, Kristopher and Clinton had left for work when Mulder went upstairs to his wife's bedroom. He said he wanted to freshen up in the adjoining bathroom before going to work. A row ensued. Downstairs, Samantha could hear her mother shouting at her father. Mulder told gardai that Colleen said he wasn't a proper father. "She said my days were numbered, that I was going to get done over by friends." He put his hands around her neck, by his account, "to stop the words".

At some stage their daughter came upstairs and looked into the room, but she was too upset to tell the court what she saw. When it was over, Mulder went downstairs and phoned a solicitor in Dunshaughlin. Then he waited, one of his three daughters on his knee, the other two lapping around, life as they all knew it having just ended.

He pleaded guilty to manslaughter, but not to murder. The jury found that he had murdered his wife. In sentencing Mulder to life imprisonment last Wednesday, Justice Philip O'Sullivan told him it was a sad day for his family.

At the back of the court, Kristopher Mulder's arms were raised in triumph.

Sitting across the bench from the defendant, Colleen's sister Ann sobbed with relief at the guilty verdict.

Outside, Kristopher said if justice hadn't been done, he would have taken justice into his own hands. His four sisters are now being cared for by their 73year-old grandmother, but Kristopher hadn't seen them for a few months.

Then William Pollock, Colleen's brother, who had been banned from the precincts of the courthouse for the duration of the trial, showed up and hugged Kristopher. Pollock said justice had been done. Pollock and his wife were banned after an attempt by Pollock to make himself "familiar to a member of the jury". He had also been briefly jailed on the opening day of the trial after an outburst against Mulder.

Soon after Pollock's appearance for the cameras, his wife hovered into view.

Next, Johan De Waal joined in the celebrations. The group linked arms and walked up the road for the photographers. Sometime later, Mulder was escorted out to a prison van to begin his life sentence. Now 44, he will serve at least 12 years before any chance of release under licence. That's a lot more than he had envisaged when he shared his thoughts on the prospect of murdering his wife.