The Ulster IRA, with the tacit but covert assistance of Michael Collins (head of the new Irish Free State) continued to wage a guerrilla war in Northern Ireland.
According to historian Alan Parkinson, despite "the IRA having some short term successes ... the main effect of this intensive campaign was to unleash a terrible backlash on the Catholic population in Belfast".
[5] About ten police officers in Brown Square Barracks, upon hearing of Turner's murder, took a Lancia armoured car and went touring Catholic areas.
[8] The attackers then used a sledgehammer to break into the house next door, where they found Joseph Walsh (39) in bed with his seven-year-old son Michael and his two-year-old daughter Bridget.
[10] Michael Collins sent an angry telegram to Northern Ireland Prime Minister James Craig, demanding a joint inquiry into the killings in accordance with Clause 5 of the recently signed Craig-Collins Pact.
[11] As with the McMahon killings one week earlier, it was strongly suspected that an RIC Detective Inspector, John William Nixon, operating out of the Brown Street Police barracks, had organised the attack.
[12] Bishop (later Cardinal) MacRory had no doubts that a cover-up was staged in the case of the Arnon killings and stated: "I believe not a single man will be arrested".
[13] According to Parkinson, "the raw sectarianism of many violent acts during this period were not confined to large scale incidents such as the Arnon Street or the McMahon murders, nor indeed to any one political or religious group".