Robert McCartney, a Roman Catholic father of two from the Short Strand area of east Belfast, was killed on the night of 30 January 2005 following an altercation at Magennis' Bar on May Street in Belfast city centre. The fight began after McCartney was accused of making an insulting gesture or comment toward the wife of an IRA member. When McCartney's friend Brendan Devine refused to accept the accusation, a brawl broke out. McCartney, attempting to defend Devine, was attacked with a broken bottle, dragged into nearby Verner Street, and then beaten with metal bars and stabbed. Both McCartney and Devine had their throats cut; McCartney's injuries included the loss of an eye and a large wound running from his chest to his stomach. He was found unconscious on Cromac Street by a police patrol car and died in hospital the following morning at age 33. Devine survived and was hospitalised under armed protection.
Police efforts to investigate the scene were disrupted by rioting that forced officers to withdraw, delaying the initial investigation. There have been suggestions that this rioting was organised by those involved in the killing to allow a clean-up of the scene. Clothing worn by the attackers was reportedly burned, CCTV tapes were removed from the bar and destroyed, and bar staff were threatened; no ambulance was called for the victims. The subsequent murder investigation encountered what has been described as a "wall of silence," with none of an estimated seventy witnesses coming forward. Seventy-one people reportedly told family members they had been in the pub's toilet at the time of the attack, a claim mocked given the toilet's small size. Sinn Féin subsequently suspended twelve party members, and the IRA expelled three members.
The killing produced significant political fallout. Sinn Féin president Gerry Adams urged witnesses to come forward to the family, a solicitor, or another "reputable person or body," stopping short of urging direct contact with police. On 8 March 2005 the IRA issued a statement acknowledging that four people were directly involved, that two were IRA volunteers, and that it had offered to shoot those involved—an offer the McCartney family rejected. The McCartney sisters campaigned publicly for justice, meeting US President George W. Bush and senators including Hillary Clinton and John McCain during 2005 St Patrick's Day events, and later meeting UK Prime Minister Tony Blair. The family said the killing had been ordered by a senior IRA member. Sinn Féin lost a council seat in the Pottinger area in May 2005, which the family attributed to the case.
On 5 May 2005, Terence Davison was charged with McCartney's murder and James McCormick with attempting to murder Devine; the attempted murder charge against McCormick was later dropped in favour of a charge of causing an affray. At trial in Belfast Crown Court, Davison was charged with murder alongside affray charges against McCormick and Joseph Gerard Emmanuel Fitzpatrick. On 27 June 2008, Mr Justice Gillen found Davison not guilty of murder, and the two men charged with affray were also cleared. The McCartney family faced sustained intimidation in the Short Strand area, causing relatives, including McCartney's former fiancée Bridgeen Hagans, to relocate; the last sister left the area on 26 October 2005. In May 2015, Gerard "Jock" Davison, believed to have been involved in McCartney's death, was shot dead; police ruled out sectarian or dissident republican involvement early in that separate investigation.