Detectives investigating the murder of mother-of-three Jennifer Dornan are considering seeking the extradition of man arrested across the Irish border.
The 30-year-old was found stabbed to death in her burning house in west Belfast last Sunday.
A 37-year-old man detained by Irish police in Co Donegal on Friday on an unrelated matter is understood to be a suspect in the murder.
The PSNI said they are no longer looking for anyone in the region in relation to the killing.
In regard to the man in custody in Donegal, a PSNI spokesman added: “There are a number of options we will now be considering to progress this investigation and seeking an extradition order is one of these options.”
Ms Dornan’s house in Hazel View in the Lagmore area was so badly damaged by the fire the roof collapsed.
Officers believe the killer torched the property in a bid to destroy evidence. Ms Dornan was the mother of two boys and a girl – all aged under nine.