VICKI SMITHCHARLESTON, W.Va. (AP) â¿¿ West Virginia mine safety officials were to release the final report on a 2010 explosion that killed 29 miners Thursday just as federal prosecutors turn up the heat on managers they say contributed to the tragedy. Families of those killed will gather in Beckley to receive the fourth report on the Upper Big Branch mine blast â¿¿ this one from the state Office of Miners Health Safety and Training. The report will be made public after the families are briefed. Previous reports â¿¿ issued by the Mine Safety and Health Administration, the United Mine Workers of America and an independent panel appointed by the former governorâ¿¿ all concluded that Virginia-based Massey Energy let explosive methane and coal dust build up in the mine, and that worn and broken cutting equipment ignited it. The release comes a day after federal prosecutors charged the mine's former superintendent with fraud and signaled they are going after other former Massey employees. Gary May, 43, was charged with conspiracy to defraud the government, accused among other things of disabling a methane gas monitor, falsifying safety records and using code words to tip off miners underground about surprise inspections. May is the highest-ranking company official charged in the 2010 disaster, and he is apparently cooperating with prosecutors, who said the investigation is far from over. He could get up to five years in prison if found guilty. The only other Massey Energy employee prosecuted so far in the nation's deadliest mining disaster in four decades is former mine security chief Hughie Elbert Stover, who will be sentenced next week for lying to investigators and trying to destroy documents. Prosecutors are urging a federal judge to make an example of Stover by giving him the maximum â¿¿ 25 years in prison. Another mine official, Thomas Harrah, was sentenced last year to prison time for using a fake foreman's license when he conducted safety reviews. That case was discovered during the blast investigation but the violations were from 2008 and 2009 and Harrah was not working at the mine when the fatal explosion happened.