It has been alleged Statement that the British , Irish , and US intelligence agencies had information which could have prevented Preventing_or_letting the bombing Terrorism , most of which came from double agents inside the Real IRA , but this information was not given Giving to the Royal Ulster Constabulary ( RUC ) .

A 2001 report by the Police Ombudsman said Statement that the RUC Special Branch failed to act on prior warnings Warning and criticised Judgment_communication the RUC 's investigation of the bombing Terrorism .

A 2001 report by the Police Ombudsman said Statement that the RUC Special Branch failed to act on prior warnings Warning and criticised Judgment_communication the RUC 's investigation of the bombing Terrorism .

The fighting Hostile_encounter was between residents of the Bogside area ( organised Arranging under the Derry Citizens ' Defence Association ) , and the Royal Ulster Constabulary ( RUC ) along with local unionists .

They were the highest-ranking RUC officers to be killed Killing during the Troubles .

The shootings were part of a string of attacks on Catholics and Irish nationalists by the `` Glenanne gang '' ; an alliance of loyalist militants , British soldiers and Royal Ulster Constabulary ( RUC ) police officers .

Billy McCaughey , a police officer from the RUC Special Patrol Group , admitted Reveal_secret taking part and accused Rewards_and_punishments another officer of being involved .