Kseniia Petrova was detained for four months after arrest with research samples, and feared deportation to Russia

Federal prosecutors have dropped all criminal charges against a Russian scientist who spent four months in immigration detention after flying into Boston with frog embryos intended for cancer research at Harvard Medical School.

Kseniia Petrova, 31, was arrested in March 2025 after returning from a vacation in France, where she had visited a laboratory specializing in cutting extremely thin sections of frog embryos. During her visit, she obtained a package of samples for her research back in the US.