A 53-year-old Oklahoma man says $50,000 worth of heroin found during a customs inspection at Detroit Metropolitan Airport was intended as a pain reliever for his ailing grandmother.

Federal authorities say Stevan Patong Thao was arrested after arriving about noon Sunday on a flight that originated in Laos and stopped in Narita, Japan.

Thao was caught transporting two pill bottles containing 490 heroin capsules. Thao said he had a prescription for the illegal drugs, then said his nephew bought them in Laos and were intended for his diabetes and high blood pressure. Authorities say both stories were false.

Thao was released on $10,000 bond and is headed back to Oklahoma.

Federal authorities and Thao's lawyer, Leroy Soles, declined comment to the Detroit Free Press.

A Jan. 27 hearing is scheduled.