The murder of Breda Cummins by her ex-partner just weeks after she ended their relationship is a classic example of "extreme domestic violence" that could have been prevented, according to retired Detective Inspector Gerry O'Carroll.
But McDonald's chilling words and actions were "almost a carbon copy of cases of domestic violence that I've investigated", Mr O'Carroll told an international conference on domestic violence in Dublin, where he was a panelist.
"Normally when the relationship breaks up it's a very dangerous time for the wife or the partner," he told the Irish Independent.
"It's on a level of danger that is nine on the Richter scale. It's at that moment when tempers explode and where he'll kill and he'll commit unspeakable violence, even knowing that he'll be caught,"
But in all too many cases, women end up being killed because they don't report domestic violence or testify against their partners before it escalates to murder, said Mr O'Carroll.