Mines inspectors were never shown Pike River Coal's log books, which recorded soaring methane levels and gas sensors that had allegedly been tampered with before the November 19 explosion.
At the Royal Commission of Inquiry today (Wednesday), former inspector Kevin Poynter was presented with a long list of serious incidents, but it was the first time he had seen them.
Mr Poynter carried out seven underground mining inspections from 2008, gaining only a "snapshot''. In 2009, he carried out only one inspection.
Royal Commission lawyer James Wilding today revealed methane levels in the top of the fan shaft had spiked several times, with a cluster in October 2010, a month before the explosion.
This meant methane levels would have been even higher inside the mine itself.
Mr Poynter said he could not give that the urgent attention it needed because the company never told him, even though they should have been notifiable events.
It showed the mine was having issues controlling gas and with ventilation, he said.
Documents also suggest Pike River Coal deliberately drew fresh air across a gas sensor, and in another case blew compressed air on to one. Mr Poynter learned of this today.
"With the benefit of hindsight, I look at these ... high potential incidents ... it just seems to me that these issues need to be out so we can see them and deal with them.''
He was also unaware the company's own logs reported the ventilation fan had gone off repeatedly in May 2010, machinery cut-off switches were not working (possibly deliberately), and some phones were out of order. Mr Poynter said he had not picked up a phone to check if they were working.
The methane drainage was blowing out because of problems with water traps, and a roadway was a "bloody mess'' with trip hazards.
Just before his last visit, on November 2, the mine had recorded lots of methane around the underground machinery.
Mr Poynter did not know a cigarette lighter had been found in a vehicle, cigarette butts in the mine, and aluminium drink-can tabs. However, it kept happening so random searches were introduced.
On one visit, he did notice a `dead man' lever on a bolting machine had been tied down, disabling a safety device.
Rather than investigate, he requested mine manager Doug White investigate.
"The deputy was suspended and ultimately was dismissed.''
Mr Poynter never inspected the main fan, and only inspected the accident register on one visit.
The Department of Labour's two inspectors reported to different managers, one of whom had no coal background.
"There was no co-ordinated approach'', Mr Poynter said.
Family members present today were clearly distressed as the number of unreported incidents piled up.