A fresh inquest will be held into the death of a woman who was murdered by her boyfriend, after her parents won a High Court challenge.
Susan Nicholson was killed by Robert Trigg in 2011, five years after he had killed his previous partner, Caroline Devlin, in similar circumstances.
Neither of the deaths were initially deemed as suspicious by Sussex Police.
Ms Nicholson’s parents campaigned for a new inquest to investigate if police failed to adequately protect her.
Trigg, 54, was jailed for life in 2017 for the murder of Ms Nicholson and manslaughter of Ms Devlin at their homes in Worthing, West Sussex.
Following the conviction, the High Court quashed the findings of accidental death in the original inquest into Ms Nicholson’s death and ordered a new one.
But West Sussex’s senior coroner ruled it would be a short inquest, with no witnesses questioned.
The new full inquest, ordered under the European Convention on Human Rights, will take an in-depth look at whether the police failed to protect Ms Nicholson’s life, a spokeswoman for her parents, Elizabeth and Peter Skelton, said.
Lord Justice Popplewell and Mr Justice Jay allowed Mr and Mrs Skelton’s challenge, ruling that a full inquest must take place.
The judges said their ruling did not mean that the police “were in fact guilty of any failings, or in breach of the operational duties”.
They said: “Our conclusion is merely that that can credibly be suggested, so that an inquest should look into whether that is so.
“It may find that no criticism of the police is justified, or that any criticisms are isolated failures and not serious. That will be a matter for investigation at the inquest.”
Mr Skelton said the family were “so relieved that the court has come to this decision” and hoped the new inquest would provide the answers they needed.
He added: “Susan was cruelly taken away from us nine years ago, and yet it has taken this long for the authorities to be questioned about the role they played in her death.”