MSHA released its final report on December 6, 2011, concluding that flagrant safety violations contributed to a coal dust explosion. It issued 369 citations at that time, assessing $10.8 million in penalties. Alpha Natural Resources, which had bought Massey Energy in 2011, settled its corporate criminal liabilities with the U.S. Attorney for $209 million.[8] Investigation of possible personal criminal liability continues,[8] with one former superintendent, Gary May, pleading guilty in March 2012, and "confess[ing] to conspiring to 'impede the [MSHA]'s enforcement efforts'".