McALLEN – A South Texas doctor has agreed to pay the United States $2,133,959.30 to resolve allegations he fraudulently submitted claims to the Medicare program for medically unnecessary diagnostic tests, announced U.S. Attorney Ryan K. Patrick. “This settlement reflects our continued resolve to protect the Medicare program from exploitation,” said Patrick. “We will vigorously pursue providers who subject vulnerable patients to medically unnecessary and wasteful services in order to boost their profits and will not hesitate to bring enforcement actions when necessary.” Dr. Augusto Castrillon is a family physician who, until recently, owned and operated the Castrillon Family Clinic in Mission. The U.S.