The Police Ombudsman has delivered a scathing report highlighting the failings on the part of PSNI officers preceding the brutal murders of Caron Smyth and Finbar McGrillen.
It is a shocking case that will shake confidence in the PSNI's commitment to protect victims of domestic violence and the effectiveness and oversight of its procedures.
The bodies of Ms Smyth (40) and her friend Mr McGrillen (42) were discovered in the living room of an apartment in the Ravenhill Court area of Belfast on December 13, 2013.
The pair had been subjected to a horrific attack consistent with being punched, kicked and stamped on.
Their killers were Sean Hegarty and Ciaran Nugent who were sentenced to life terms in 2015.
Caron Smyth had told police just days before she was murdered that she was frightened Hegarty was going to kill her.
The ombudsman investigated this case and how police dealt with Hegarty, a violent offender who was on bail for alleged involvement in a knife attack on a relative.
His bail address was Ms Smyth's home but when police went to the house to carry out a check they left after getting no response from the front door, even though Hegarty's electronic tag showed he was at the property.
In fact, Ms Smyth later reported he had been holding her against her will and had assaulted her with an iron bar before she managed to escape.
Police arrested Hegarty for assault and breach of bail but the following day released him to a different address, even though only a court can authorise such a change and it later transpired the new property did not have the electricity supply needed to operate his electronic tag, but no prior check was carried out.
Six police officers have now been disciplined while the PSNI has apologised but this does not change the tragic outcome of this profoundly disturbing case or lessen the grief of two families who have lost their loved ones.
