`We are 36 days not eating and our stomachs are devouring themselves," wrote Ruth Mulrooney in a last appeal to her sister Josephine, in June last year. Aged only 53, Ruth would be dead within a week, curled up in her blue nightdress beside the marble fireplace in the living room, her rosary beads around her neck.

In agonising pain, fearful of being judged as neglectful of their 83-year-old aunt, conscious that their sanity and dignity were ebbing with every hour, Ruth was the sister who tried to stop the madness. Perhaps she had more insight into the starvation process than the others. While in her 20s, Ruth had been part of a yoga group that believed fasting for up to 40 days could lead to perfect health.

An old friend who remembered meeting her at a vegetarian gathering in the 1970s described her as one of the most gentle people he had ever met, kind, spiritual and intelligent, not the type to contemplate suicide.

Whatever her misgivings, Ruth clearly felt constrained in what she could say within the group. Though they shared the same fetid living-room and kitchen day and night in the last days, she felt obliged to put her desperate appeals to Josephine in written form.

After 36 days of starvation, she wrote: "I wonder if we should call the hospice in Harold's Cross. We could say that we had cancer, but we can't let the nurse see auntie like this as they will think we can't look after her."

By now, their aunt probably already had the bronchial pneumonia, brought on by starvation, which would kill her a few days later.

"None of us could have foreseen our deaths would be so cruel and slow, and while the idea of ascending into heaven together is a good one, we did not envisage this. . . Let's think of exiting ourselves sanely and with dignity. It would be cruel and neglectful not to intervene." She had received correct guidance in the past, she said: "If we do not do something now, we will not go peacefully into the night."

But while Ruth had clearly changed her mind about the "exiting" method, she remained confident about the decision to die. Despair about earthly life and visions of eternal happiness on a higher plane were the motivators in a house distinguished in neighbours' eyes by the untidy garden and constantly changing religious images in the front window.

In letters addressed to two friends, written a few days before her death, she asked them not to grieve for her: "There is no happiness here on Earth. Everything is transient, unlike in the higher realm. Until we meet again, I will watch over you . . ."

The letters were found under a pillow in the front bedroom.

The exit had been carefully planned. The three sisters and their 83-year-old aunt, Frances, lived on welfare benefit, yet when two of them took a taxi home from a last shopping trip in Dublin's St Stephen's Green Centre to the rented house in Leixlip on March 31st, they told the driver to look after his children before tipping him £20 on top of his £30 fare.

They took their aunt - whom they frequently called "Mammy" and for whom they had changed their names by deed poll - to the bank and the post office. They paid £100 into their ESB account, leaving it £31.47 in credit where it would normally be a few pence, and wrote to social welfare authorities to say that they would sign on in Maynooth in April.

Then these physically healthy women went home, blocked the hall door with a fridge and sealed the letter box, pushed a table and chair to the back door and turned the heating up to stifling in high summer, before retiring to starve themselves to death.

Frances was the first to die, around June 15th. Ruth was next, some two days later. Josephine lasted for another 12 days or so and the last, Ruth's twin, Catherine, probably died a day after that. It was two weeks later before the landlord finally gained entry.

The scene laid before him could hardly have been further from Ruth's vision of a sane and dignified exit; three grossly emaciated bodies scattered on the floor of the foul-smelling living-room amid buckets of urine; another, Catherine, in the kitchen propped up on bean bags. Like Ruth, she, too, had rosary beads around her neck.

HOW could such a tragedy happen in the global village? How could women noted for their kindness to cats and stray birds, for their devotion and deference to their elderly aunt, decide on such a savage course?

As people cast around for answers, and one politician called for the "proactive policing of vulnerable people", the one certainty is that these women were not simply abandoned by an uncaring society. Three of them were able-bodied and still only in middle age. The State paid the bulk of the rent for a new, warm and spacious house, an improvement on their previous accommodation in Tritonville Road, Sandymount.

Their sister, Theresa, had accommodated them over Christmas 1998, between the move from Sandymount to Leixlip. There three parish workers had tried to visit the house. A social welfare inspector had called three times and was concerned enough to alert the Garda. A garda also called and failed to gain admission.

In the end it was the landlord who, when his registered letter was returned to him, forced his way past the fridge blocking the front door and discovered the bodies.

Could anything else have been done? From a social perspective, psychologist Maureen Gaffney describes the tragedy "as a kind of unintended consequence of the extreme value that we now put on privacy. There were always eccentric people around who were always isolated to some degree. But if you have multiple inter-activity, you have a kind of safety net. People notice if you weren't at Mass or down to collect the paper or out walking.

"But in modern society with its sprawling suburbs with long commuting times, added to the extreme value put on privacy, it's possible that such people can become invisible and completely forgotten about. You rely on people's wish to become invisible in society, but that's fine when you're young, independent, healthy, drive a car. . . It's a disaster if you're at the two extreme ends of the life-cycle i.e. very old or very young.

"The case of young Jamie Bulger is not so different from what happened in Leixlip. It's not that people are so bad and uncaring, but so many people saw that child being dragged along crying for two miles, yet not one of them managed to get over what is seen as the worst thing you can do now, which is to invade someone's privacy".

A St Vincent de Paul spokesman echoed this view when he called for people to start "poking their noses in a bit if they have worries about their neighbours. The risk of a rebuke would be worth it if it helped to avert a tragedy such as this".

Yet, perhaps because of their short tenure in Leixlip (about 18 months) and increasing isolation, there were no patterns for caring neighbours to observe. For example, although Mass attendance had been routine in Sandymount, in Leixlip local priests never saw them at church. In any event, three of the four were by no means at the extreme end of the life-cycle, and back in Sandymount years of experience had taught the neighbours that a "rebuke" would be the least of it if they stuck their noses in.

A MAN who mistakenly knocked on the door a few years ago finally had it opened to him after much scraping and dragging of objects inside. The dark-haired woman who appeared asked angrily why he was there.

When he asked if this was No 96, she shouted that it was not. How dare he disturb people at this time of the morning, calling unannounced, sneaking about, prying into people's homes. She repeatedly demanded his name and threatened the police on him. Workmen who went to carry out house repairs tended to leave prematurely, unnerved by the eccentric habits and erratic moods of the residents. Even the local shopkeeper knew better than to knock when he made deliveries; he left them at the door.

For all the paranoia - the unanswered calls, the drawn curtains - there remained a loneliness and a need to communicate, however minimal. The estate agent who dealt with the women said they struck her as "very lonely people". The landlord, to whom the rent arrived intermittently but "near enough" to the due date, often got letters from Josephine: "To be honest, I just think she liked to write letters".

No one can know for certain what dynamic propelled the four women towards such a death, but Ruth's note to Josephine suggests that this was a suicide pact.

"It is a most unusual kind of pact," says Maureen Gaffney. "Usually such a pact is between two lovers, say, or mass cult suicides. But we do know from those that they are more likely to happen when a number of circumstances operate simultaneously.

"When people become extremely socially isolated, we know certain things happen. Feelings can become very exaggerated and overwhelming, but mainly the outcome is that otherwise intelligent and rational people with a slight psychological frailty can resort to desperate measures. As a result of the social isolation, they can turn in on themselves and become extremely dependent on each other.

"Then there is an air of siege or crisis, usually some air that something terrible is going to happen, as for example with that cult which believed it was going to be invaded by the CIA, which heightens emotions in this very excluded group. And there is always a very strong personality at the centre.

"Combine these circumstances, and you have an explosive mix. In the Leixlip case you had the extreme social isolation, the high dependency between them, the crisis with the woman whom they regarded as their mother, to whom they deferred and talked of as taking care of them, who was in changing health, which for them became an overwhelming crisis."

The outstanding question this week is, short of breaking the door down, could it have been prevented? Where should society draw the line between concern for able-bodied people and invading their privacy?

We all know of cases where even family members are loath to pry into each others' affairs. So we can only guess at the burden of grief behind the words read out to this week's inquest by the solicitor for the surviving family members: "This has been a very difficult time for them."