A seriously injured man, who walked into a Sydney police station, alerted police to the death of his sister whose body was then found in a house on NSW's south coast.
The 46-year-old man spoke to officers at Gladesville police station shortly after 5.30am local time.
He was taken to Royal North Shore Hospital with a stab wound to the chest, NSW Ambulance said.
Police from Wollongong Local Area Command were alerted and found the body of the woman at the house in Hobart Street, Bulli, about 5.40am.
"Police were alerted to a possible murder about 5.30 this morning," Sergeant David Munro from Wollongong police station, said.
"We just got a call to say this person was at the address and apparently deceased."
Sergeant Munro said he "would imagine" the woman was found with stab wounds but could not confirm this.
He said the pair were brother and sister.
The man is helping police with inquiries and is expected to be charged, Sergeant Munro said.
A crime scene has been established at the Wollongong home and an investigation in now under way.
Gladesville police station in Punt Road has been cordoned off.
Forensics services officers have inspected a white Ford laser parked outside the police station and have covered the car with a blue tent. The driver's seat appears to have blood stains on it.
The man was in a serious but stable condition, a Royal North Shore Hospital spokeswoman said.
The distance from Bulli to Gladesville is about 76 kilometres.
Neighbour Samantha McCauley, who lives a few doors down from the house with her mother, said the dead woman was in her early 40s and was the daughter of a couple who live at the house.
"They are lovely people and often have garage sales," Ms McCauley said.
"There are always cars outside the house. Mum once saw [the woman] at a garage sale."
She said the woman and her family often came down from Sydney to visit her parents.
Another neighbour, who did not wish to be named, told the Illawarra Mercury they didn't hear anything unusual on Thursday night.
They said the pair were well known in the neighbourhood. They were originally from the area, then moved away for several years before moving into the Hobart Street house about four years ago.
The neighbour said the brother and sister occasionally had their problems but were always polite and friendly to everyone else.
- FFX Aus