Gary May was sentenced in January to 21 months in prison on a conspiracy charge for his actions at the former Massey Energy Co.'s Upper Big Branch Mine.
U.S. Bureau of Prisons records showed Tuesday that May has reported to the minimum-security prison for men.
The 44-year-old Bloomingrose resident pleaded guilty last year to charges that he defrauded the government with actions that included disabling a methane gas monitor and falsifying records.
May has cooperated with prosecutors in their continuing criminal investigation of the worst U.S.
