Police say they know where the man at the centre of a triple killing in Dunedin obtained the gun used but will not reveal further details.
The body of 51-year-old Milton prison worker Edward Livingstone was found at the house in the suburb of St Leonards where he is believed to have shot his son Bradley and daughter Ellen, aged nine and six, on 15 January.
A police spokesperson would not elaborate about the weapon on Monday, saying the details are an important part of the investigation, which is due to last a few weeks.
Details of the children's funeral have been released, with a service planned at their school, St Leonards, on Saturday afternoon.
In 2013, Mr Livingstone was arrested twice for breaching a protection order for his former wife, Katharine Webb, 49, but was discharged without conviction.