CHARLESTON, W.Va. -- State investigators plan to release their report on the Upper Big Branch Mine Disaster on Feb. 23, officials confirmed Friday.The state Office of Miners' Health, Safety and Training investigation is the last unfinished government report on what caused the April 5, 2010, explosion that killed 29 miners at a Massey Energy operation in Raleigh County.Agency officials are planning to provide the report to families of the miners who died during a private morning meeting at the Raleigh County Convention Center in Beckley, said spokeswoman Leslie Fitzwater.The report will then be made public when it is released that afternoon at a meeting of the state Board of Coal Mine Health and Safety, Fitzwater said.UBB reports by special investigator Davitt McAteer, the U.S. Mine Safety and Health Administration and the United Mine Workers union have already been released.MSHA officials have yet to release their separate "internal review" meant to examine agency actions -- and inactions -- at Upper Big Branch prior to the disaster.Reports from McAteer, MSHA and the UMW have generally agreed that the explosion involved an ignition of methane that a buildup of coal dust underground turned into a major disaster.Government and independent investigators have blamed the disaster on Massey's failure to follow basic safety rules governing mine ventilation and the control of highly explosive coal dust. They also cited the company's failure to perform periodic safety examinations and fix problems identified, a systematic effort to warn underground workers of impending inspections and intimidate workers so they wouldn't complain about hazardous conditions.MSHA cited the company for 369 safety violations -- including 12 that directly contributed to the disaster -- and levied more than $10.8 million in fines.Alpha Natural Resources, which bought Massey in June 2011, agreed to pay those fines as part of a $200 million settlement. As part of that deal, U.S. Attorney Booth Goodwin agreed not to bring any criminal charges against the company, but said he would continue to pursue cases involving individuals responsible for the disaster. Reach Ken Ward Jr. at firstname.lastname@example.org or 304-348-1702.