A Bucks County doctor has admitted running a “pill mill,” selling diet pills without a prescription. 47-year-old emergency surgeon Christopher Vassalluzzo of Upper Makefield pleaded guilty to a drug charge, mail fraud and tax evasion Monday in federal court in Philadelphia. A federal indictment says he evaded paying taxes on more than $2.3 million he made selling pills. The indictment says his operation went on for about a decade out of a Northeast Philadelphia weight loss center, and he evaded taxes by paying employees “under the table.” He had a practice in Lansdale at one time. He will serve 34 months in prison and forfeit more than $5 million, four homes and several vehicles.