INDIANAPOLIS — A former Indiana scientist accused of illegally sending trade secrets worth $300 million to China and Germany was ordered detained Tuesday on rare charges of economic espionage.

A federal indictment unsealed in Indianapolis alleges that 45-year-old Kexue Huang, who was born in China, passed on proprietary information about the development of organic pesticides to Hunan Normal University while he worked as a researcher for Dow AgroSciences in Indiana from 2003 to 2008.

Assistant U.S. Attorney Cynthia Ridgeway said Huang, a Canadian citizen with permanent U.S. resident status, used a “patient and calculated” plan to “drain” the Indianapolis-based company of technology that took 20 years to develop.

The indictment alleges that Huang published a paper in China about the organic pesticides and directed students at Hunan Normal in further research.

FBI Special Agent Karen Medernach testified that e-mails showed Huang was developing an operation to market the pesticides in China, where he stood to make millions of dollars. She said the agency believed that Huang stole samples of the bacterial strain used in the pesticides and smuggled them to China in his son’s suitcase.

The indictment also included a vague reference suggesting Huang also transported stolen material to Germany.

Defense attorney Michael Donahoe said Huang maintains his innocence.

The indictment, which had been kept secret since it was filed June 16, charged Huang with 12 counts of theft and attempted theft of trade secrets to benefit a foreign government. He also was charged with five counts of foreign transportation of stolen property.