BELFAST, Northern Ireland — The Irish Republican Army's alleged involvement in the $50 million robbery of Belfast's Northern Bank, the biggest in the annals of British crime, could almost be dismissed with a knowing wink as a kind of Robin Hood caper.

But the pub brawl that resulted in the murder of a 33-year-old Catholic man by members of the IRA has seriously tarnished the organization's image among its grass-roots Catholic supporters, especially after the victim's five sisters defied the IRA's unwritten code of silence and publicly demanded that their brother's killers be brought to justice.

The Jan. 30 slaying of Robert McCartney has underscored the increasing criminality of the IRA and dealt a serious blow to the electoral chances of Sinn Fein, the IRA's political wing.

It also has isolated Sinn Fein leader Gerry Adams and turned the McCartney sisters into local heroes. Adams has not been invited to the traditional St. Patrick's Day celebration at the White House later this month; instead, President Bush has extended the honor to the McCartney sisters and the victim's fiancée, Bridgeen Hagans.

House Speaker Dennis Hastert, R-Ill., following the White House's lead, also scratched Adams from the guest list of the speaker's annual St. Patrick's Day luncheon.

And in its bluntest criticism yet of the IRA, the Bush administration yesterday told the organization it should disband.

"It's time for the IRA to go out of business," said Mitchell Reiss, the U.S. envoy to Northern Ireland. "And it's time for Sinn Fein to be able to say that explicitly, without ambiguity, without ambivalence, that criminality will not be tolerated."

He particularly questioned Sinn Fein's claim that most IRA activities — including robbing banks and shooting petty criminals in the limbs — shouldn't be considered crimes. He said Sinn Fein should begin cooperating with the Northern Ireland police, a mostly Protestant force that once suffered heavily from IRA attacks, and today is being substantially reshaped with support from moderate Catholics.

"The support of the White House in our quest for justice will be a big help," said Paula McCartney, a 40-year-old mother of five and part-time university student.

"Punishment shooting"

In an extraordinary admission of just how damaging the incident has become for the IRA, its leadership on Tuesday issued a statement saying it had met with the McCartney sisters and offered to impose a "punishment shooting" on the four men it says were directly responsible for McCartney's death.

Two of the four are said to be IRA members. Punishment shootings are the IRA's preferred method of rough justice. Normally, they are not fatal.

Sinn Fein leader Gerry Adams: off the guest list.

The sisters rejected the offer.

Exactly what triggered that argument in Magennis' Pub the night of Jan. 30 remains in dispute. Robert McCartney, an amiable forklift operator, and his friend, Brendan Devine, a club boxer with a reputation for brawling, got into an altercation with the IRA group over an alleged insult to a woman in the pub.

By most accounts, McCartney, an amateur bodybuilder and occasional nightclub bouncer, tried to act as peacemaker. But knives were drawn and Devine's throat was slashed. When McCartney tried to drag his bleeding friend from the bar, they were followed outside by a dozen men with knives and metal pipes.

Devine's torso was sliced open and McCartney was stabbed in the chest. Both were savagely beaten and left for dead. Devine survived, but McCartney didn't. The IRA men then returned to the pub, wiped it down for fingerprints, mopped up the blood and destroyed the film from the pub's security cameras. The 70 or so patrons in the pub were advised, "This is IRA business."

"The right thing to do"

The message was crystal clear, but the McCartney sisters refused to be intimidated.

"We didn't really think about it. We just knew it was the right thing to do," said Paula McCartney. The other sisters are Gemma, 41, a nurse; Donna, 38, who runs a catering business; Catherine, 36, a history teacher; and Clair, 26, a teacher's aide.

The sisters' demand that the IRA be held accountable for the murder has sent shock waves through this bleak working-class neighborhood known as the Short Strand.

A Catholic enclave of about 3,000 residents in the heart of predominantly Protestant East Belfast, the Short Strand is ringed by a 30-foot-high "peace wall," a concrete-and-steel reminder of the hatreds that endure despite the Good Friday peace agreement.

The IRA, which killed about 1,800 people from 1970 until its 1997 cease-fire, relied on support from its Roman Catholic base as it mounted attacks on businesses, British troops and the predominantly Protestant police force. In the decades before the peace agreement, Short Strand residents — the McCartney family among them — viewed the IRA not only as their protectors from Protestant paramilitaries, but also as the enforcers of law and order within the Catholic community.

The group ensured its control of the toughest Catholic quarters by attacking petty criminals and killing people accused of helping the police — or in some cases merely for homing in on IRA criminal rackets or insulting an IRA figure.

Such IRA bullying has persisted with relative impunity for 35 years because virtually no Catholics have been willing to testify against IRA figures.

Under terms of the Good Friday agreement, the IRA should have disarmed and disbanded several years ago. Instead, the unemployed gunmen have turned themselves into an increasingly mafialike crime organization, specializing in drug dealing, extortion, money laundering and the occasional bank robbery.

"Fund raising" was how IRA sympathizers characterized such activities.

But the McCartney slaying has challenged that view. More than 1,000 people attended his funeral. Reaction to the killing could mark a turning point.

The IRA, under pressure from the sisters, last week announced the expulsion of three members. The sisters have given Sinn Fein leader Adams a list of seven more alleged accomplices.

Adams, who acknowledges that he personally knows some of those on the list, has suspended them from Sinn Fein and handed the list to a police ombudsman, an act tantamount to treason by IRA custom. Adams has also said that witnesses should come forward.

But so far, none has.

"Obviously, people are being intimidated," said Paula McCartney.

"We've spoken to some of the witnesses. They say they've been told to go to the police with this concocted IRA version of the story," she said.

"A couple of witnesses we spoke to were Robert's friends, and they were visibly petrified. You can understand why: They witnessed a man's throat being cut, and they know that when you've been warned to remain silent, it's not an idle threat," she said.

What most galls the sisters is that the IRA men who killed their brother are well-known in the community and even today seem to enjoy a privileged status.

"These people who murdered our Robert are going about their daily lives like nothing happened. You can see them having a pint in the local pub," McCartney said.

Wary witnesses

Joe O'Donnell, the Sinn Fein city councilor for the Short Strand, praised the sisters for their courage, but said he also understood why witnesses were reluctant to come forward.

"I understand the reality of what it is like to live in a community that suffered for 35 years at the hands of the police," he said. "But we want people who have information to come forward, and we're telling them that if they have this difficulty [going to the police], then they should go to a priest or a [lawyer]."

In its statement Tuesday, the IRA said it had spoken to key witnesses and told them they had nothing to fear.

The Northern Ireland police commander, Chief Constable Hugh Orde, said the IRA claim to be investigating the crime was "an absurd sideshow."

"The IRA killed Robert McCartney. They intimidated the witnesses. They destroyed the evidence," said Orde, whose detectives have arrested 10 suspects but released them without charge after they refused to speak. "Everyone knows who the suspects are — we certainly don't need an illegal organization to tell us. What we need is witnesses unafraid to identify them in an open court."

Another man was arrested yesterday on suspicion of involvement after he walked into a Belfast police station accompanied by a lawyer. Police identified him as one of the recently expelled IRA members.

A string of setbacks

The McCartney mess couldn't come at a worse time for Sinn Fein. The peace process has been suspended since 2002, when police discovered the IRA was operating a spy ring inside the Northern Ireland government offices. The process was dealt a further setback after authorities blamed the IRA for the spectacular $50 million robbery of Belfast's Northern Bank just before Christmas.

Although no one has been charged in the robbery and the IRA denies any involvement, police investigators have uncovered a massive IRA money-laundering operation in the Republic of Ireland.

Irish Prime Minister Bertie Ahern has accused Adams and his top deputy, Martin McGuiness, of being senior commanders in the IRA — something they have always denied — and suggested they may have known about plans to rob the bank.

Ahern and other politicians in the south, once staunch backers of Sinn Fein, have moved to distance themselves from Adams. And now, so has the White House.

On the defensive

Next week, Adams is scheduled to visit several U.S. cities as part of Sinn Fein's regular fund-raising activities in Irish-American communities. The trip is still on, but fund-raisers have been canceled.

Last weekend, Sinn Fein held its centenary party conference in Dublin. It should have been a valedictory moment for Adams. Sinn Fein has emerged as the largest nationalist party in Northern Ireland, and before the McCartney slaying, it seemed poised for strong electoral gains in the south as well.

But instead, Adams was on the defensive. He tried to salvage the situation by inviting the McCartney sisters to sit with him in the front row at the conference.

"Those responsible for the brutal killing of Robert McCartney should admit to what they did in a court of law," Adams told the party faithful. "I am not letting this issue go until those who have sullied the Republican cause are made to account for their actions."

The sisters did not applaud. They later said that while they appreciated Adams' words, they would hold their applause until their brother's killers were brought to court.

Information on the IRA's history as well as yesterday's developments was reported by The Associated Press.