Scientist who brought frog embryos to Boston for cancer research is
cleared of smuggling charges
[November 05, 2026]
By MICHAEL CASEY
BOSTON (AP) — U.S. prosecutors have dropped all criminal charges against
a Russian scientist who was tossed into an immigration jail last year
after she landed at a Boston airport with frog embryos intended for her
cancer research at Harvard Medical School.
Kseniia Petrova, 31, spent four months in detention following her arrest
in early 2025 as she returned from a vacation in France, where she had
stopped at a lab specializing in splicing superfine sections of frog
embryos and obtained a package of samples for research.
She was questioned about the samples while passing through a customs
checkpoint at Logan International Airport, then later charged with
smuggling.
A federal judge on Wednesday granted a request by prosecutors to dismiss
those charges as well as counts alleging that she'd concealed facts and
made false statements to government officials.
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.
The case began to fall apart in April, after a federal judge ruled a
customs officer improperly canceled Petrova's visa over the incident.
Petrova had feared being deported to Russia and imprisoned there.
Her lawyers had also argued that the criminal prosecution was
vindictive, saying the government only filed criminal charges after it
looked like she would win her immigration case. They also argued that it
was rare for anyone to be charged criminally for what Petrova did.
On Tuesday night, U.S. Attorney Leah Foley filed a motion to dismiss the
charges “based on developments in this case and an assessment of the
office’s priorities and resources.”
“At this stage, the resource costs of continuing this prosecution
outweigh the public interest in its resolution,” she wrote, adding that
the “defendant’s claims of vindictive and selective prosecution are
meritless.”
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Harvard University researcher Kseniia Petrova departs the John
Joseph Moakley United States Courthouse after being released on bail
from federal custody on June 12, 2025, in Boston. (AP Photo/Leah
Willingham, File)
 U.S. District Judge Leo Sorokin, who
was nominated by former President Barack Obama, dismissed the
charges Wednesday without a hearing.
“The DOJ never should have brought this highly unusual “smuggling”
prosecution against Kseniia Petrova, a talented scientist at
Harvard,” one of Petrova's attorneys, Daniel Marx, said in a
statement. “Ms. Petrova only sought to advance medical research into
aging that could benefit everyone, and her handling of scientific
samples — inert, non-living, non-toxic, frog embryos — never posed
any danger to anyone.”
Earlier this year, the Department of Homeland Security defended
Petrova's detention, saying she had lied to federal officers about
the frog embryos.
In a court filing asking the judge to dismiss the case, Foley cited
an April court ruling that would have allowed Petrova's lawyers to
get broad access to government documents as part of her defense that
she was being prosecuted selectively.
“The government must supply the defendant with information
pertaining to any number of passenger encounters involving
undeclared items that could be considered comparable, without regard
for the manner in which those items were carried, the presence or
absence of planning, or the strength of the evidence of a
passenger’s fraudulent intent,” Foley wrote.
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