West Palm Beach, Fla. -- Investigators who raided the offices of Rush Limbaugh's doctors said in search warrants filed yesterday said that the conservative radio commentator engaged in illegal drug use and "doctor shopping" for prescription painkillers. The warrants -- which name four doctors and several prescription drugs -- show investigators were looking for records including prescription disbursements, appointment schedules, receipts and a medical questionnaire when they raided the offices Nov. 25. Mr. Limbaugh denied any wrongdoing to listeners on his radio show earlier yesterday and accused prosecutors in Palm Beach County of going on a "fishing expedition." AP