COLUMBUS, Neb. -- A top fire official in northeast Nebraska has resigned.

Columbus Fire Chief Dan Miller is leaving the position after four years on the job. The Columbus Fire Department confirmed the departure to NCN.

Miller previously served as Battalion Chief in the Omaha Fire Department and has 28 years of career service.

His resignation comes less than a week after it was revealed a coal fire had been smoldering at the Columbus Archer Daniels Midland facility for three or four weeks.

A News Channel Nebraska investigation uncovered several questions concerning the fire.

The Columbus Fire Department had been informed of the fire at that time, but the public only found out after a news release from the East-Central District Health Department encouraged residents in the "immediate vicinity" to take precautions against possible exposure to carbon monoxide.

The ECDHD release said the health department had notified the Nebraska Department of Environment and Energy of the situation at ADM.

Four people were tested for carbon monoxide poisoning, with two testing positive.

Miller was the first ever full-time fire chief in Columbus.