ALEXANDRIA, Va. (AP) — Customs agents were alarmed at their discovery last August at Dulles International Airport: an undeclared cooler packed in a suitcase and filled with 10 test tubes of an unknown yellowish substance, brought to the U.S. by a woman claiming to be a Russian scientist.

Authorities scrambled to uncover the truth: The woman was indeed a respected Russian scientist. The test tubes were not dangerous, but contained DNA samples of endangered species, including Siberian crane, that were related to her work as a geneticist with the Institute of Molecular and Cellular Biology in Novosibirsk.

On Thursday the scientist, Polina Perelman, was sentenced to probation and a $1,000 fine at federal court in Alexandria in a case that authorities hope will serve as a reminder to scientists to follow the proper protocols when transporting scientific samples.

“You didn’t think it was a big deal. It is a big deal,” said U.S. District Judge Patricia Tolliver Giles, who imposed the sentence.

Assistant U.S. Attorney Cristina Stam was the duty officer on the night that airport authorities called prosecutors to alert them to the potential danger. At Thursday’s sentencing hearing, she recalled the level of concern as agents “scrambled to figure out if what was before them was dangerous.”

“No one knew exactly what they were dealing with,” she said.

Customs officers found the test tubes in a Styrofoam cooler marked “RESEARCH SAMPLES” and packed with dry ice. Under federal law, there are procedures for bringing DNA samples into the U.S., even if they are from endangered species. But Perelman admitted during her guilty plea earlier this year that she did not want to declare her package to Customs because she thought it would result in delays and unwanted questions.

Perelman, 48, a Russian citizen but also a permanent U.S. resident living in the Washington, D.C., suburb of Leesburg, apologized Thursday for her conduct and to “the agents who were scared at all those tubes.” As she continued to speak, she began to deflect blame, saying she never lied to agents and that her answers to the interrogation she received after the tubes were discovered were misinterpreted.

But Giles cut her off and reminded her that she admitted as part of her plea bargain that she made a conscious decision to evade Customs requirements. She said Perelman should have understood the sensitivities of undeclared vials of biological material in a post-pandemic world.

Her lawyer, Mark Cummings, emphasized that the endangered species samples of Siberian crane and dhole — an Asian wild dog deemed a threatened species — were properly obtained from a zoo, and that her work was designed to help those species, not hurt them.

The sentence of probation and a fine was in line with prosecutors’ request as well as federal sentencing guidelines for a first-time offender.