Police have yet to formally identify a body found in a Wellington council flat on Wednesday afternoon.
It is thought to be that of a woman in her 40s or 50s, who had recently moved into the block of flats in Newtown.
Police say they have no suspects at present, but are treating the death as suspicious.
They want to hear from anyone who saw activity in the area in the past week.
A post-mortem is being carried out on Thursday evening.
It is the second suspicious death on the street in less than a year.
Last August, a homicide inquiry took place when a man's body was discovered at a home for the mentally ill, also on Mansfield Street.