A man yelled "What have we done?" as he fled the home of Upper Hutt woman Lois Tolley on the night of her killing, police say.
The 30-year-old was stabbed and shot at point-blank range in her home on 10 December.
Police were seeking for four men, but said it was possible one or more women were involved.
They released details yesterday of the men and two vehicles, based on CCTV footage officers have reviewed.
Detective Senior Sergeant Glenn Barnett said officers were still trying to establish a motive for the killing.
"One of the members of this group did stop outside the address after the murder and was believed to be quite upset, calling out loudly, 'What have we done? Oh no,' and stuff like that."