The United Mine Workers union has released its own report into last year’s deadly explosion at West Virginia’s Upper Big Branch Mine. The report is highly critical of the way non-union Massey Energy handled the disaster.The explosion killed 29 workers, and the title of the report instantly gives a sense of how the United Mine Workers of America views the disaster: it’s called Industrial Homicide.After the blast, the UMWAwas designated an official representative of coal miners in the non-union mine. In the report, the union predictably criticizes Massey Energy, saying equipment wasn’t well-maintained and safely operated. It also faults federal regulators for not shutting the mine down.But the report does contain two new pieces of evidence about the explosion, which evidence suggests was caused by a methane ignition fed by coal dust. The UMWA report notes the specific placement of a curtain in the mine, which could have directed fresh air directly to a methane monitor. This would have prevented the monitor from detecting unsafe levels of methane and shutting down equipment.It also mentions the presence of a clean, undamaged methane sensor from an area damaged by the blast. The report implies the sensor could have been planted after the explosion by Massey officials who were underground at the time.Massey Energy was sold to Alpha Natural Resources earlier this year.