A 26-year-old man has been arrested in Dublin on suspicion of the murder of 22-year-old Mary Ward who was found dead in south Belfast.
Ms Ward was found by police at her home in Melrose Street on 1 October.
The Police Service of Northern Ireland (PSNI) has since started a murder investigation.
Assistant Chief Constable Davy Beck said the investigation was progressing at pace and police were still trying to establish the exact circumstances of Ms Ward’s death.
An Garda Síochána (Irish police) said it would continue to work closely with police in Northern Ireland.
Timeline
Ms Ward died from a number of wounds to her neck, BBC News NI understands.
Her body was found by police officers who went to her house on Tuesday 1 October – but it is believed she was killed on or around 25 September.
The PSNI had been in contact with her on a number of occasions in the previous weeks.
This began on 4 September when she made a complaint to the police about being the victim of violence.
Providing details of the timeline of events, Ass Ch Cons Beck confirmed on Wednesday that police had a phone call with Ms Ward on 10 September.
He said officers attempted to speak to her on 24 September and spoke to her by phone on 25 September. This was the last contact police had with her.
Officers attended the property regarding an unrelated matter on 1 October, he said.
“That’s when we observed a female crouched over against the upstairs front window of that house and located Mary deceased unfortunately within the property,” Ass Ch Cons Beck said.
“We initiated an investigation into the unexplained and suspicious death.
“That investigation was lead by detectives, that was a complex investigation that involved scene examination, detailed forensics, post-mortem which brought us to the point where we were in a position to confirm that this was a murder on 4 October.”
Details of the murder investigation were not released until just before midnight on Monday.
It is believed the PSNI had determined a number of days ago that Ms Ward had been murdered.
Police believe Ms Ward was last seen alive on 25 September.
Speaking on Wednesday, Ass Ch Cons David Beck said he was “absolutely appalled” that there had been another murder of a woman in Northern Ireland.
He said: “Too many women are losing their lives at the hands of men”.
“We are absolutely determined that we will be relentless in our pursuit of the perpetrators and cannot allow another woman to die as a result of violence at the hands of men.”
Police Ombudsman
Police confirmed on Tuesday that following a review of its previous engagements with Ms Ward the case had been referred to the ombudsman.
The Police Ombudsman’s Office said the focus of its investigation would be on the police response to a report of violence in the weeks leading up to her death.
It confirmed the case was referred to it by police on Sunday night.
Violence against women
Det Ch Supt Lindsay Fisher has said Ms Ward was the fourth woman to be killed in Northern Ireland in the last six weeks.
Combating violence against women and girls (VAWG) has been rising up the list of police and political priorities recently.
Two years ago, the PSNI launched an action plan.
This was followed by an Executive Office strategy published last month, in response to the fact that more than 30 women and girls have been murdered in Northern Ireland in the last five years.
In the 12 months to July, the PSNI recorded 22,400 VAWG-related offences.
The PSNI has said this is a 16% drop year-on-year and shows some progress is being made.
However, it accepts there is still much to be done by it – and wider society.