Pike River families are urging more people to come forward with information about the 2010 disaster after six-year-old video footage was leaked of the inside of the West Coast coal mine.
Sonya Rockhouse, whose son Benjamin died in the mine, said a large amount of information about the fatal gas explosion and its aftermath was yet to be publicly released.
"There's quite a few people that have information that for whatever reason haven't come forward," she told Newstalk ZB.
"And we're trying to encourage people that if you know anything, good or bad, you need to come forward so the whole truth can come out."
A month ago, the families were leaked footage taken from inside the mine's drift three months after a gas explosion killed 29 workers. It was released to Newshub yesterday.
Filmed by a camera on a robot, the footage shows two Mines Rescue staff working in the drift, which is filled with methane.
Rockhouse said it should have been shown to the Royal Commission of Inquiry into the disaster in 2012.
"Surely it would have been a piece of footage that the commissioners and all the lawyers and everybody should have seen, including the families."
Police, which controlled the mine at the time the video was taken, said it was not supplied to families of victims or the Royal Commission because it was assessed as having no evidential value.
Its release on Sunday has prompted the Government to check whether it was properly disclosed by police and whether it contained any new information.
Rockhouse said the leaked footage vindicated the families' belief that the mine's drift could be safe to re-enter.
"Now we have the proof that what we've been saying all along is correct."
She was shocked at the footage because she expected the mine's drift to be more severely damaged.
Acting Conservation Minister for Pike River Issues Nick Smith said it was no secret that people had been a few hundred metres inside the drift, or that the tunnel was still in a good condition despite the explosion. But he has asked officials for clarification about the video's contents and how much of it was disclosed.
The Government is looking at unmanned re-entry of the drift, but has ruled out manned re-entry on health and safety grounds.
Police Minister Paula Bennett revealed in February there were 24,000 images held by Government agencies on Pike River.
However, police had not received any requests to release the footage, she said.
The families have since sought these images under the Official Information Act.
Police have delayed its response on the grounds that the more time was needed to research and collate the information.