Gary May, 44, was sentenced in January to 21 months in prison on a conspiracy charge for his actions at the former Massey Energy operation.  U.S. Bureau of Prisons records show that May has reported to the minimum-security prison for men Tuesday.  May pleaded guilty last year to charges that he defrauded the government with his actions that included disabling a methane gas monitor and falsifying records. 

May has cooperated with prosecutors in their continuing criminal investigation into the worst U.S. coal mining disaster in 40 years.  He even testified at former Massey Security Chief Hughie Stover's sentencing.