The doctors included Walter Neil Simmons, 47, of Gilbert, Ariz., emergency medicine doctor who has worked at two metro Phoenix hospital chains. He was indicted in October in U.S. District Court in Dallas on one count of conspiracy to commit health-care fraud. The federal charge carries a maximum sentence of 10 years in federal prison and a $250,000 fine.

When reached by phone this week, Simmons said, "I can't make any comments."

Federal prosecutors said the scheme involved prescribing "compounded" drugs such as pain, scar and migraine creams to military families covered by Tricare, the federal health insurance program for active-duty and retired military and family members.

There have been at least two other federal probes alleging pharmacies paid kickbacks to doctors who ordered expensive compounded drugs for patients. One involved a California pharmacy that billed the state's worker's compensation program for pricey markups. In another, a Florida doctor was indicted on a charge of taking kickbacks for sending prescriptions, which billed Tricare and Medicare for creams that cost as much as $21,000 for a one-month supply, according to a federal indictment.