A U.S. grand jury indicted Russian scientist and Harvard Medical School researcher Ksenia Petrova on three charges of smuggling frog embryos, false statements and concealment of a material fact, the U.S. Justice Department said Wednesday.

The indictment stems from a Feb. 16 incident when customs officials stopped Petrova at Boston Logan International Airport upon her return from France with the biological samples.

Immigration authorities revoked Petrova’s research visa and transferred her between multiple detention facilities before formally charging her with smuggling last month.

Petrova’s attorney, Gregory Romanovsky, had told The Moscow Times that the smuggling charge was “outrageous and legally indefensible,” arguing that the non-living frog embryos were not classified as restricted biological materials under U.S. customs law and did not require a permit.