A federal judge on Wednesday dismissed all criminal charges against Kseniia Petrova, a Russian-born biomedical researcher at Harvard Medical School, ending a case that had drawn scrutiny over the handling of undeclared biological samples at Boston’s Logan International Airport.
Federal prosecutors filed a motion to drop the charges on Tuesday, stating that continuing the prosecution would divert resources from higher-priority federal interests. The dismissal followed a ruling in April by a federal judge that a customs officer improperly canceled Petrova’s J-1 scholar visa, which had been revoked after her February 2025 detention.
Petrova, 31, was held in immigration custody for four months after customs officials at Logan Airport questioned her upon her return from France, where she had obtained research samples. The samples included clawed frog embryos, paraffin slides, and other biological materials intended for cancer research. Prosecutors initially charged her with smuggling, concealment of material facts, and making false statements.
In court filings, U.S. Attorney Leah Foley cited resource constraints as the reason for dropping the case, stating that the resource costs of continuing the prosecution outweighed the public interest in its resolution. Petrova’s defense team had argued the prosecution was vindictive and selective, asserting that criminal charges were filed only after her immigration case appeared likely to succeed.
Petrova maintained that she was unaware the samples needed to be declared and had no intent to violate U.S. customs regulations. Her attorney, Daniel N. Marx, called the prosecution “highly unusual” and stated that Petrova’s handling of the samples—described as non-living, non-toxic, and inert—posed no risk.
The dismissal came one day after prosecutors filed their petition to drop the charges, following a federal magistrate judge’s order allowing Petrova to obtain evidence supporting her claims of selective prosecution. Prosecutors argued that providing such evidence would require disclosing non-public information about U.S. Customs and Border Protection operations.
Petrova’s case had become a focal point amid broader debates over immigration enforcement and the treatment of foreign researchers in the United States. Earlier this year, a judge in Vermont ruled that Petrova’s visa was unlawfully canceled, a decision that contributed to the unraveling of the criminal case.
The dismissal concludes a legal ordeal that began in February 2025 and left Petrova in immigration detention for months. Her attorneys emphasized that she had sought only to advance medical research into aging, a field with potential benefits for public health.