Kseniia Petrova, 31, had faced federal charges after customs officials discovered undeclared frog embryo samples in her luggage when she arrived at Boston Logan International Airport in February 2025.

Petrova was returning from a trip to France, where she had collected the biological samples from a laboratory specialising in preparing extremely thin sections of frog embryos. The materials were intended for research at Harvard Medical School, where she worked on studies involving cancer, ageing and disease.

Following the discovery, US authorities accused her of smuggling goods into the country, concealing material facts and making false statements to federal officials. She spent nearly four months in immigration detention before being released on bail in June 2025.

Petrova maintained that she did not know the samples needed to be declared at customs and insisted that she had no intention of secretly bringing prohibited materials into the United States.

The case took a significant turn in April 2026 when a federal judge ruled that US Customs and Border Protection had improperly cancelled her visa over the incident. Her legal team also challenged the criminal prosecution, arguing that the government had selectively targeted her and that similar customs violations rarely resulted in felony charges.

On Tuesday, November 3, US Attorney Leah Foley filed a request to dismiss the criminal case, citing developments in the proceedings and the resources required to continue the prosecution.

The government argued that the cost of pursuing the case had become greater than the public interest in continuing it, although prosecutors maintained that Petrova’s allegations of selective and vindictive prosecution were without merit.

On Wednesday, November 4, US District Judge Leo Sorokin approved the request and dismissed all charges without a hearing.

Petrova’s legal team welcomed the decision, describing the prosecution as unnecessary and arguing that the scientific samples were non-living, non-toxic and posed no danger to the public.

The dismissal brings an end to a lengthy legal battle that threatened Petrova’s scientific career and raised questions about the treatment of international researchers working in the United States.

The case has also drawn attention to the challenges scientists face when transporting biological research materials across international borders, particularly when customs declaration requirements are involved.