The man in charge of the investigation into the Gleision Colliery disaster has said that nothing more could have been done to establish what happened.
Speaking exclusively to ITV Cymru Wales for tonight's Wales This Week programme, the Acting Chief Inspector of Mines Steve Denton said he is satisfied that the Health and Safety Executive did everything it could.
That comes despite criticism, from the families of the four miners who died in September 2011, that they were not thorough enough - and a public inquiry is now needed.
There is much more on this story on:
Wales This Week, tonight at 10.35pm on ITV Cymru Wales
Y Byd Ar Bedwar, tonight at 9.30pm on S4C
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Cloudy with outbreaks of rain and strong winds too. The rain persistent and at times heavy over high ground.
After a mostly dry evening with a few scattered showers, cloud and outbreaks of showery rain will spread northeast through the night.
Tributes have been paid to former Wales international Mel Charles, who has died at the age of 81.