A Newshub investigation has discovered police destroyed 52 exhibits that were found around the Pike River Mine after it exploded.
The exhibits include parts of breathing units, an ESR report, clothing, and even earplugs - items that could have belonged to some of the 29 men.
Police are also trying to locate part of a circuit board that was blown from the mine’s vent shaft. Newshub has been told this could be part of the control panel - a vital item of evidence - police have admitted losing.
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But while police decided the items had "no evidential value" and could not have been used in court, families of the dead say it "beggars belief" and they want answers.
"Publically, we want to know who gave the order to destroy all this evidence and we want to know why," said Dean Dunbar, the father of Joseph Dunbar who died in the mine.
Obtained under the Official Information Act, photos show exhibits that were binned - less than five years after the tragedy. Documents reveal even an overall sleeve was found near the vent shaft.
"So there were items there that were items of clothing which could have been the last point of contact for families with their dead children," says Richard Healey, an investigator and Pike Families supporter.
Police say the sleeve was cut, not torn, and had no signs of burning.
But families of the dead, including Bernie Monk, say such items could have belonged to their sons and should have been DNA tested.
"Never even consulted on any of the things that they've found, or any of the things that they've done. They've just told us nothing," says Monk.
Dunbar says some of that evidence "would have proved that there were survivors".
"You have got parts of self-rescuer units that have been destroyed."
Photos show part of the rescuer or breathing unit he's talking about. There's also a valve from a face mask. Both were washed out of the mine after the second explosion and could have been tested for DNA - that didn't happen.
Police say "it was determined that DNA evidence would have had no value in this case apart from in a Disaster Victim Identification response".
But Dunbar says "we've got to pay attention to what the reality of this is, and it's a cover-up."
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Newshub revealed police notes in February that described the way they gathered evidence as "diabolical". Now we know they destroyed exhibits they decided "had no evidential value".
"It's troubling. It indicates a reasonably relaxed view to the handling of evidence," says independent investigator Tim McKinnel.
He says evidence is generally only disposed of if there are storage issues or if exhibits present a health and safety risk.
"Outside of those issues, I can't see why you would begin destroying items from a potential crime scene when so little is known about what happened there," he says.
Police will not say who exactly ordered the items be destroyed. But the lead police investigator only found out about it late last year.
"Why would they destroy that, without even consulting the lead investigator?" asks Dunbar.
While the official police line is that the items were not of value, a senior detective on the case has personally told Dunbar and Monk destroying exhibits was a mistake.
"One cop that wasn't involved in the investigation that is now apologised and said that he was sorry and that it was wrong to do that," Dunbar says.
Police have recently reopened their investigation into Pike with plans to re-enter later this year. But Monk says what's needed is an independent investigation.
"The country deserves to know the truth," he says.
Almost nine years on, they're unwavering in their determination to uncover what really happened in the dark depths of the West Coast coal mine.