Judge Dismisses Frog Embryo Smuggling Case Against Harvard Scientist Kseniia Petrova

A federal judge on Wednesday granted a government motion to dismiss all criminal charges against Kseniia Petrova, a Russian-born scientist at Harvard Medical School who was accused of smuggling frog embryos into the United States.

Petrova, 31, had been indicted last year on one count of concealment of a material fact, one count of false statement and one count of smuggling goods into the United States. US District Judge Leo Sorokin, who was nominated by former President Barack Obama, dismissed the charges on Wednesday without a hearing.

Prosecutors asked to end the case

On Tuesday night, US Attorney Leah Foley filed the motion to dismiss, writing that she based it on "developments in this case and an assessment of the office's priorities and resources." Foley wrote that "the resource costs of continuing this prosecution outweigh the public interest in its resolution," and she added that the "defendant's claims of vindictive and selective prosecution are meritless."

The case began on February 16, 2025, when Petrova returned to Boston from a vacation in France. She had stopped at a French laboratory that specializes in splicing superfine sections of frog embryos and had obtained a package of samples for her research. Officers questioned her about the samples at a customs checkpoint at Logan International Airport. Petrova told the Associated Press in an interview that she did not realize the items needed to be declared and was not trying to sneak anything into the country.

Four months in detention

A customs officer canceled Petrova's visa over the incident, and she spent four months in immigration detention in Vermont and Louisiana before she was released on bail on June 12, 2025. She had feared being deported to Russia and imprisoned there. The Department of Homeland Security defended her detention earlier this year, saying she had lied to federal officers about the frog embryos.

Prosecutors brought the criminal case in May 2025, while a federal judge in Vermont was weighing whether to order her release from detention. Her lawyers argued that the prosecution was vindictive, saying the government filed criminal charges only after it looked as if she would win her immigration case, and that criminal charges are rare for what she did.

The case came apart in court

In April 2026, a federal judge in Vermont ruled that the customs officer had improperly canceled Petrova's visa. A judge in Boston later sustained a decision that she had put forward enough evidence of selective prosecution to gain broad access to government records for her defense. In her filing, Foley cited that April ruling and wrote that it would require the government to supply information about large numbers of passenger encounters involving undeclared items.

Daniel Marx, one of Petrova's attorneys, said in a statement: "The DOJ never should have brought this highly unusual 'smuggling' prosecution against Kseniia Petrova, a talented scientist at Harvard." Marx said her handling of the samples never posed any danger to anyone and described them as inert, non-living and non-toxic.

The dismissal closes the criminal case that followed Petrova for more than a year and a half. Neither report on Wednesday announced any change to her separate immigration proceedings.