The man in charge of the investigation into the Gleision mining tragedy has said nothing more could have been done to establish exactly what happened.
Watch the full programme Wales This Week: Tragedy at Gleision
Speaking exclusively to Wales This Week, the then Acting Chief Inspector of Mines, Steve Denton, said:
Mr Denton said the plans of the mine being used by manager Malcolm Fyfield had turned out to be "pretty accurate."
At the trial of Malcolm Fyfield and MNS Mining, which owned Gleision, the defence team claimed the Health and Safety Executive had sealed the mine before other experts had had a chance to do their own investigations.
Mr Denton told ITV Wales that 'disaster tourists' had been constantly trying to approach the mine.
Last week, mine manager Malcolm Fyfield and owners MNS Mining Ltd were cleared of manslaughter charges over the death of four miners in September 2011.