A relative of twins Chris and Cru Kahui says he is trying to organise a meeting this weekend to encourage family members to reveal who killed the babies.
Robert King, a brother of the twins' mother, Macsyna King, said he met police yesterday and was told the investigation was moving
very slowly.
The 3-month-old boys died on June 19 after suffering skull fractures and brain damage.
Whanau members have refused to say who was responsible.
Mr King said the family wanted police to "leave them alone" but he had told the relatives: "They won't leave you alone until somebody is accountable for hurting our babies."
He said he did not know who inflicted the fatal injuries. He had given police an undertaking he would try to organise a hui this weekend.
Inquiry head Detective Sergeant John Tims said police still needed to talk to family members but he said they had been "fine, no problems there. We've been speaking to them and clarifying facts. There are still things we need to ask."
Mr Tims said that next week police hoped to get the final results of the post-mortem examination and of medical tests done by paediatricians who looked after the babies before they died.
A retired detective inspector who was involved in more than 100 murder investigations says the public should not give up hope of an arrest for the killings.
Graham Bell said the Kahui situation was not uncommon in police inquiries.
"I've struck several inquiries in my time where you get everybody involved telling you lies."
But stonewalling would not stop an inquiry. "You just keep going and eventually you'll get to the bottom of things," he said.
- additional reporting NZPA
