Mine Workers Pres. Cecil Roberts adds the agency was also victim of lack of funds and mis-directed priorities imposed by the GOP Bush government in the years before the blast.
Mine workers are now demanding criminal prosecution of 18 Massey Coal Company executives - including retired CEO Don Blankenship - for "industrial homicide."
On that dismal day in West Virginia history, when the Upper Big Branch mine exploded, a son of one of the miners, Eddie, went from person to person asking: "Is there any word?"
The indictment of the security supervisor at Massey Energy's Upper Big Branch will be the first of many indictments after an explosion killed 29 West Virginia miners.
"How can a nation that relies on its miners not do everything in its power to protect them?" the president said to the thousands at Sunday's memorial in Beckley, W.Va.
West Virginia coal miners stopped work April 16 to mourn the 29 killed at the Massey Energy mine, and President Obama ordered a top-to-bottom review of mine safety enforcement.
"This guy, making $30-some million in 2005, went inside the coal mine and sat down with every single worker and said: 'If you vote for the union, you're not going to have a job because I will close this mine down.'"