Police have given expert reports about the Pike River Coal mine disaster to the families' lawyers on condition that the files themselves are not released directly to the families.
Twenty-nine workers died in a series of explosions which began at the West Coast mine near Greymouth on 19 November last year.
The families have been calling for the files since Police Commissioner Howard Broad announced on 13 January that the police operation to recover the men's bodies would end.
The families' legal team on Wednesday said it received the police dossier five days ago, but is not allowed to discuss its contents.
Lead solicitor Colin Smith says the confidentiality conditions extend even to the families, who can see only a summary of the facts the Police Commissioner relied on to make his decision.
Mr Smith says the information will be sent out to the legal team's own experts to analyse whether the ending of the recovery operation was justified.
A spokesperson for the families, Bernie Monk, says he is not worried by the limitations, and says some information from the files was given out at a meeting two nights ago.
An inquest into the deaths starts on Thursday.
'No evidence of remains' on video footage
Police say video released to the families shows substantial damage to the mine and no evidence of bodies or remains.
The operation's commander, Superintendent Gary Knowles, told Morning Report that video from a slimline shaft at the end of the main shaft shows the roof has collapsed and indicates that there would be much worse damage further in.
Other footage was from a bore hole at the very back of the mine, he said.
Grey District mayor Tony Kokshoorn says in the footage taken from the bore hole, pallets and cement bags could be seen with no sign of charring, and if other areas show as little damage there is a possibility that there will be bodies to be recovered.
But the lawyer representing the families Nicholas Davidson, QC, says there is only limited footage and none shows any intact bodies.
Mr Kokshoorn says it could be two years before rescue teams can enter the mine if an idea to tunnel a new access point becomes the only option.
The mayor says mine experts say the area beyond the main mine shaft, known as Spaghetti Junction, is believed to be unstable structurally even though the atmosphere is now inert.
Mr Kokshoorn says two new boreholes are to be drilled to gather air samples and video from other parts of the mine, which will take four weeks.
One of the receivers for Pike River Coal says an idea to tunnel a new access point into the mine has not yet been explored.
John Fisk from PricewaterhouseCoopers says the receivers will take over the operation next week, but in the meantime, new boreholes are being drilled.