Criminal charges should be laid against Pike River Coal's managers and directors, some families of men killed in the explosion have said ahead of today's release of a potentially damning report expected to show profits were put before safety.
Recommendations from the royal commission of inquiry on the Pike River mining tragedy will be released this afternoon and are expected to include sweeping changes to the mine-safety regime and wider health and safety laws.
It is expected to be highly critical not just of mine management but also of slack laws and oversight. The report follows 10 weeks of public hearings over nine months and damning evidence of safety failures at the mine.
Carole Rose, mother of Pike River victim Stuart Mudge, said that with the inquiry complete, the families were hoping someone would be held culpable and manslaughter charges laid.
"Twenty-nine men died.
"We want to see charges . . . somebody is responsible for this."
The inquiry heard allegations of workplace bullying; a report showing gas levels spiked to explosive levels six times in five days, a month before the mine exploded; evidence from one former mining operator who left the company fearing the mine could explode at any moment; "impossible" workloads facing mines inspectors; a lack of enforcement action; plastic bags placed over gas sensors; a lax safety attitude encouraged by production bonuses; potentially flammable gas mixtures in an electrical substation; and safety systems inside the mine being bypassed.
Former mine manager Peter Whittall has pleaded not guilty to 12 charges laid under the Health and Safety in Employment Act.
In evidence to the inquiry, the "horrified" chairman of the Pike River Coal board, John Dow, said management - including former chief executive Gordon Ward and Whittall - had kept safety problems from the company's board.
Neville Rockhouse, a former safety manager at Pike River mine whose son, Ben, died in the explosion, was one of those who gave evidence against the company. He said the families had pushed for the commission to recommend a law change introducing corporate manslaughter to sheet home culpability in future accidents like Pike River.
"It's something they already have in Britain and Australia.
"It is something the Government seriously needs to consider - otherwise boards and executive management can make whatever decision they like and hide behind the company . . . It would draw a line in the sand."
But whatever the commission recommended, he expected the Government to act with urgency to implement any changes.
"They'd be bloody insane if they didn't . . . the bomb started ticking a long time ago for this particular mine when the Department of Labour didn't think the mining industry was worth an improved code of practice, when they disbanded the inspectorate and disbanded the mining act and its regulations."
The Pike River tragedy was described during the inquiry as "a homicide investigation of huge proportions", involving more than 200 witnesses being interviewed with another 170 still to be spoken to. A police spokesman said yesterday their investigation was ongoing and it was not known how long it would take.
The royal commission report comes as the families fly in international mining experts to help them in their bid to convince authorities that it is safe to stage a recovery of the bodies.
After promising the families he would do all he could to bring the bodies home, Prime Minister John Key has repeatedly told them the Government's experts think the mine is still too unsafe to enter.
The families will be handed copies of the report in Greymouth today but Mr Key has sent two senior ministers instead of fronting personally.
The report will also be released in Wellington and a spokesman for Mr Key said he would front a press conference to announce the response immediately after Cabinet considered the report.
WORST MINING DISASTER IN 96 YEARS
The Pike River coalmine exploded on November 19, 2010, killing 29 men.
But for days New Zealand held out hope that they would be pulled out alive from the mine, deep in the Paparoa Range, 40 kilometres north of Greymouth.
Pike River Coal's chief executive at the time, Peter Whittall, told the media that the men could be sitting around an open pipe breathing fresh air while waiting for rescue.
But when the mine exploded a second time five days after the first, all hope of rescue was lost.
It was New Zealand's worst mining disaster in 96 years.
Prime Minister John Key promised everything would be done to bring the men home.
A royal commission was announced to establish what happened and why, plus how to avoid future tragedies.
Its three appointed commissioners were chairman Justice Graham Panckhurst, a West Coast-born senior High Court judge; Stewart Bell, Queensland's commissioner for mine safety and health; and David Henry, former commissioner of Inland Revenue and the Electoral Commission.
Ten weeks of public hearings spanned nine months, starting in July last year. They were divided into four phases, with 57 witnesses giving oral evidence and more than 200 others filing written submissions. The commissioners had to consider more than 70,000 pages of evidence.
Damning evidence of safety failures was presented and the Pike River mine was labelled an "accident waiting to happen".
The Labour Department, now part of the Business, Innovation and Employment Ministry, and the Government also came in for criticism for its weakened mining inspectorate and under-regulated laws.