PETTUS, W.Va. — State and federal investigators are trying to determine what killed a 48-year-old miner found Monday at a coal mining operation in Raleigh County.

James Ray Adkins of Colcord, West Virginia, was discovered missing at approximately 7:10 a.m. at Marfork Coal Co.’s Horse Creek Eagle Deep Mine, according to the West Virginia Office of Miners’ Health, Safety and Training.

Preliminary information indicated that Adkins was later found dead from initially unknown causes in the raw coal stockpile at the Marfork Processing Plant near Pettus, the office reported.

The mine and processing plant were idled Monday. Inspectors from the state office and federal Mine Safety and Health Administration were on site.

Steve Hawkins, spokesman for parent company Alpha Natural Resources, said there appears to have been a belt haulage accident. Adkins worked at the company for 17 years, he said.

Adkins was employed as a belt man and fire boss at the mine.

The incident raises deaths in U.S. coal mining to 14 this year, half in West Virginia, according to MSHA. Eight coal miners died in workplace accidents last year.