(AP) -- FLORENCE, S.C. (AP) - A former Lake City police officer has lost an appeal of her conviction and 20-year federal prison sentence for drug trafficking and extortion.

Court documents filed Tuesday show the 4th U.S. Circuit Court of Appeals in Richmond, Va., turned down the request from former Lake City Police Sgt. Shanita McKnight.

Prosecutors said McKnight was part of a drug ring and used her position to make people pay her. They also said McKnight tipped off drug dealers on when investigators would be in town.

McKnight was sentenced in May 2009. She had faced a possible sentence of life in prison and up to $8 million in fines.

McKnight is serving her sentence at a federal medical center in Fort Worth, Texas, that specializes in mental health treatment for female offenders.

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