Police in Northern Ireland have been criticised after a prolific criminal, with a history of abuse against women, killed his ex-partner and friend three days after being released from custody.
Caron Smyth, a mother of six, and Finbarr McGrillen were beaten to death in 2013.
One of the killers, Sean Hegarty, had been arrested three days earlier.
Ms Smyth had told police she feared Hegarty would murder her days before she was killed.
Hegarty had been arrested after Ms Smyth told police he had imprisoned her, hit her with a metal bar and threatened to kill her.
Six PSNI officers have been disciplined over failures identified by the Police Ombudsman.
Caron Smyth's family say they believe she would still be alive if police had "acted properly and adequately".
They have issued legal proceedings against the PSNI.
In a statement, Mr McGrillen's partner, Tina Gillespie, and his children welcomed the report by the Police Ombudsman and said they hoped the PSNI's actions would "prevent other families suffering the avoidable loss" they had experienced.
A report, published by the Ombudsman on Tuesday, lists a catalogue of flaws in the way the police dealt with Hegarty, who is serving a life sentence for the double murder.
It said that police failed to protect his victims or to properly assess the risk he posed.
The Ombudsman, Dr Michael Maguire, said more appropriate action may have reduced the likelihood of the killings.
The PSNI said the report was "difficult reading" and has apologised to the family.
Hegarty was classified as a "violent offender" by the PSNI's systems and he had a lengthy criminal record, with more than 70 previous convictions and several allegations of abuse of former partners.
The report notes that Hegarty had been in police custody or brought to the PSNI's attention a number of times in the months leading up to the murder including:
- In January 2013, after police received a report that Hegarty had assaulted a home owner with a hammer
- In early April that year, when they received a report that he had assaulted a man in Strabane
- Later that month, he was given a prison sentence for assaulting a former partner the previous year
- In June 2013, police received a report that he was in a premises in Belfast threatening to kill a former partner
- The same month police were told Hegarty had assaulted a relative and cut the man's face with a knife
- In July, they investigated claims that he made a threatening phone call to an ex-partner and threatened a woman with a knife
- In October that year he was arrested for the alleged attack on his relative and was released on court bail
The report said that Hegarty was released from prison in May 2013 and, that summer, began a relationship with Caron Smyth, who lived in Drumaness, County Down.
As part of his October bail conditions, he was ordered to stay at Mrs Smyth's house.
'Risk of serious harm'
The weekend prior to the murders in December 2013, Hegarty was arrested again when Mrs Smyth contacted police and said he had held her captive in her home and assaulted her with a metal bar.
"Police met Caron and compiled a report which detailed her injuries, and recorded her as saying she was frightened and thought Hegarty was going to kill her," the report states.
"It concluded that she was at 'risk of serious harm'."
Sean Hegarty was arrested on Sunday, 8 December for assault and breaching the terms of his bail.
He was released on police bail the following day after PSNI officers, without authorisation from the court, allowed him to change the address where he could live.
The report says the new address did not have an electricity supply needed to operate an electronic tag that was supposed to monitor his movements.
Three days after his release from custody, on Thursday, 12 December, Hegarty and another man went to a flat in Ravenhill Court in Belfast where Caron Smyth was staying with a friend, Finbarr McGrillen.
Their badly beaten bodies were found the following day.
Hegarty, formerly of Grainne House in the New Lodge, was sentenced to life with a minimum tariff of 18 years.
'PSNI failed spectacularly'
His accomplice Ciaran Nugent, formerly of the Simon Community on the Falls Road, was given a 14-year tariff.
The trial judge, Mr Justice Weir, told them they would serve every day of their terms without remission for what they had done.
In a statement, Caron Smyth's family said Sean Hegarty should not have been released from police custody after his arrest for assaulting her.
"The PSNI will say that their purpose is 'keeping people safe', in the case of Caron Smyth, they failed spectacularly to do so," added the statement.
The Policing Board has described the report as "shocking" and said it was clear that some PSNI officers had "fallen short of expectations".
PSNI Assistant Chief Constable Alan Todd said he acknowledged that "we failed to effectively manage the risk posed to the public by Sean Hegarty".
Apologising to Caron Smyth's family, he said five recommendations made by the Ombudsman had been accepted in full.
"It may be of no comfort for the families of Caron Smyth and Finbarr McGrillen but I would reassure the public that we will be learning from this and ensure steps are taken to prevent a tragedy like this occurring again," he added.
The Policing Board has asked for an assurance from Chief Constable George Hamilton that all of the recommendations made in the report have been implemented.