The family of Robert McCartney, a Catholic whose death at the hands of Irish Republican Army members in January caused international outrage and brought White House condemnation, said Wednesday it was being subjected to a campaign of violence and intimidation for speaking out forcefully against the IRA.

Paula McCartney, Robert's sister, said her two teenage sons were beaten recently by family members of a high-ranking IRA officer who they believe was involved in McCartney's killing. On Monday night, one of Robert McCartney's closest friends, Jeff Commander, was beaten with metal rods by a gang of men the McCartney family also contends are IRA members linked to the killing.

On Tuesday night, at least 50 people, mostly women, demonstrated outside the home of Bridgeen Hagans, McCartney's fiancee, vowing to return every night until she moves out of the neighborhood.

"They want to intimidate us, they want us to keep quiet," said Paula McCartney, whose small home in the Short Strand, a close-knit Catholic community in East Belfast, is decorated with photos of well-wishers including U.S. Sens. Edward M. Kennedy (D-Mass.), Christopher J. Dodd (D-Conn.) and Hillary Rodham Clinton (D-N.Y.).

She said Commander's attackers used the recent riots in Belfast's Protestant communities as an opportunity to take revenge on McCartney's family while police and public attention were focused elsewhere.

Mitchell B. Reiss, President Bush's special envoy to Northern Ireland, described the situation as "disgraceful."

"We deplore the recent violence and intimidation against the McCartney family, Bridgeen and their friends," Reiss said Wednesday in a statement to The Washington Post. "It is unacceptable and should stop immediately."

McCartney, a supporter of Sinn Fein, the IRA's political wing, was killed Jan. 30 in a pub brawl after an argument got out of hand. He was dragged outside and beaten by at least a dozen men, one of whom stabbed him in the heart.

In a remarkable departure from the code of silence enforced by the IRA among its Catholic supporters, McCartney's family publicly and repeatedly said that he was killed by IRA members and demanded justice. They said the IRA intimidated witnesses to keep them from coming forward and sent in professionals to clean up the murder scene and destroy evidence.

The family's campaign -- which included a visit with Bush at the White House -- badly embarrassed Sinn Fein and damaged its reputation as it fought an increasing perception that the IRA was tainted by thugs and criminals who lacked their forefathers' political ideals. Trying to stem the political damage, Sinn Fein's leader, Gerry Adams, invited the family to address a party meeting, where they issued impassioned demands for justice.

The IRA took the unusual step of publicly denouncing the McCartney killing and offered to shoot those responsible in the kind of rough justice it has long used to police Catholic communities. The McCartney family rejected that offer. Two men have been charged in connection with McCartney's murder, and the IRA announced it had expelled three members over the killing. In July, the IRA announced it was laying down its weapons for good.

Sinn Fein issued a statement Wednesday denying any link to the beating of Commander, whose bloodied head was featured in several front-page newspaper photos in Belfast on Wednesday. "Sinn Fein is totally opposed to intimidation of any type no matter where it comes from or who it is aimed at," said the statement issued by a party official, Gerry Kelly.

But in the Short Strand, an IRA stronghold where about 3,000 people live in modest two-story brick buildings, McCartney's family said IRA intimidation was still a way of life.

Even as the IRA has disarmed and lost much of its former clout, individual IRA members still "act as if they can do anything they want," said Jim Arnold, Paula McCartney's husband. "It's an absolute disgrace," said Arnold, a house painter. "They are dinosaurs. They live on the back of the IRA, but the IRA are finished, and they cannot grasp it. They won't move on."

Arnold said the people who took part in the McCartney killing are well known in the Short Strand. And he said that despite the IRA's claims that the men were expelled, they are still deeply involved with the paramilitary group. "This district is sickened by these people still parading around who were involved in Robert's murder," he said.

Arnold said these men joined a crowd of Catholics who gathered at the entrance to the Short Strand on Monday evening, standing guard against any rioting Protestants who might try to come in and cause trouble. He said they were also among the men who ambushed Commander later in the evening, opening a large gash on his head.

"They're trying to tell our family: Shut up or this is going to happen again," Arnold said. "The McCartney family opened a lot of eyes in Belfast."

Arnold and Paula McCartney, as well as Bridgeen Hagans, are making plans to move out of the neighborhood. "I can't live in a community where it is perfectly acceptable to murder an innocent man and still walk around freely," Paula McCartney said.

Robert McCartney, above, was killed Jan. 30 by IRA members at a Belfast pub. His sister Paula, right, says her sons were beaten recently by family members of a ranking IRA officer.