Michael Dean "Fireball" Roberts, 54, of Saltville, pleaded guilty to charges of distribution of methamphetamine, cocaine, oxycodone and hydrocodone.
Roberts is scheduled to be sentenced Oct. 9 in U.S. District Court for the Western District of Virginia in Abingdon. Roberts faces up to 20 years in prison and a maximum fine of $1 million.
According to the U.S. Attorney's Office for the Western District of Virginia, Roberts distributed the drugs over a seven-year period that ended in 2013.
Roberts was employed as the town of Marion's police chief the entire time, U.S. Attorney Timothy Heaphy said.
An investigation carried out by local, state and federal authorities determined Roberts sold at least 7,331 hydrocodone pills and 365 grams of methamphetamine, as well as smaller amounts of cocaine and oxycodone.
Heaphy said Roberts used his position as police chief to obtain some of the drugs from the police department's evidence room.
As part of the investigation, agents with the ATF, FBI, DEA, Virginia State Police and Washington County Sheriff' Office used a confidential information to obtain hydrocodone pills from Roberts on three separate occassions spanning from May to June 2013.
Roberts is the second Southwest Virginia police chief this year to plead guilty in federal court to drug-related offenses that occurred in the line of duty.
In May, former town police chief William Bryan Young was given a nine-year prison sentence at a hearing in federal court in Big Stone Gap.
Young was also ordered to pay more than $11,000 in restitution.
Young pleaded guilty in January to charges of distributing narcotics while on duty and orchestrating the robbery of the town's Rite Aid Pharmacy.