A detention center in Louisiana is jammed with around 90 immigrant women, mostly workers without legal documentation from Central and South America, sharing five toilets and following orders shouted by guards.

There is also, among them, a Russian scientist.

She cannot work, because her laptop was confiscated. She plays chess with other women when the guards allow it. Otherwise, she reads books about evolution and cell development.

For nearly eight weeks, Kseniia Petrova, 30, has been captive to the hard-line immigration policies of the Trump administration. A graduate of a renowned Russian physics and technology institute, Petrova was recruited to work at a laboratory at Harvard Medical School. She was part of a team investigating how cells can rejuvenate themselves, with the goal of fending off the damage of aging.

On Feb. 16, customs officials detained her at Logan International Airport in Boston for failing to declare samples of frog embryos she had carried from France at the request of her boss at Harvard.

Such an infraction is normally considered minor, punishable with a fine of up to $500. Instead, the customs official canceled Petrova’s visa and began deportation proceedings. Then Petrova told her that she had fled Russia for political reasons and faced arrest if she returned there.

This is how she wound up at the Richwood Correctional Center in Monroe, Louisiana, waiting for the U.S. government to decide what to do with her.

Petrova’s case is being watched by thousands of highly educated Russians who, like her, fled the country after Russia invaded Ukraine. It has also caught the attention of prominent figures in Russia’s political opposition who warn that, for the United States, delivering a dissident scientist to President Vladimir Putin would be crossing an especially foreboding line.

For her part, Petrova is seeing the United States from a new and unsettling vantage point. “I feel like something is happening generally in America,” she said, in an interview over a video link. “Something bad is happening. I don’t think everybody understands.”

Immigration and Customs Enforcement has twice refused her lawyer’s petition for parole, contending that she is a flight risk and a threat to U.S. security.

Harvard has made little comment about Petrova’s detention. A spokesperson said this week that the university “is closely following the rapidly shifting immigration policy landscape and the implications for its international scholars and students,” and is “engaged with Ms. Petrova’s attorney on this matter.”

Petrova is not giving up on her work. As she awaits her hearing, she is studying meiosis, a type of cell division that allows egg and sperm cells to reset epigenetic marks, pointing the way to possible strategies to stop aging. All she can think of is getting back to her laboratory.

“I was in paradise,” she said. “I would very much like to stay in paradise.”

On Feb. 24, 2022, when Putin sent Russian tanks across the border into Ukraine, Petrova joined protests in Moscow’s streets. On March 2, she was arrested, charged with an administrative violation, fined about $200 and released.

It was clear that things were changing quickly, Petrova said. The handful of news sources she relied on for objective information “closed immediately,” she said. Petrova feared the border would close as well. She left the country two days later.

She said that after this, it became “really obvious” that if she wanted to be a scientist, she had to leave: “I changed my decision from ‘I will never leave Russia’ to ‘I am leaving Russia immediately.’”

Leon Peshkin, a principal research scientist in Harvard’s department of systems biology, had been looking to hire someone for a year.

The Kirschner Lab, where Peshkin works, is investigating the earliest stages of cell division. These changes are easy to observe in the eggs of the xenopus frog, which are large and hardy.

Peshkin’s team is interested in sperm and egg cells, and how they repair damage as an embryo develops. They needed someone equally fluent in machine learning and cell biology, Peshkin explained in an online community for data scientists. Petrova reached out.

When she arrived in Boston in May 2023, Peshkin was shocked to discover that she had not brought a suitcase; she carried a backpack. It became clear, he said, that she was “extremely ascetic,” entirely wrapped up in her research.

“I thought the Russia of my childhood was gone, the Russia of this crazy, dedicated, ascetic scientist is gone,” he said. Over the months that followed, Peshkin watched her focus intensely for many hours; he saw what she could pull off in a few days of coding. “She is probably strongest I’ve seen,” he said. “I am at Harvard for 20 years.”

Peshkin worried she would burn out. He was relieved when she told him she was taking a vacation to France, where pianist Andras Schiff was giving a concert.

She would also make time for work. Peshkin collaborates with a laboratory in Paris, where one of the scientists had figured out how to slice superfine sections of a frog embryo.

No one at Harvard knew how to do it; high-quality samples would substantially speed up their work. A few times, their French colleagues had tried to mail the embryo samples, but they thawed in transit and arrived too damaged to use.

“I said, ‘Well, you’re there,’ ” Peshkin said. “Why don’t you get this package?”

Petrova’s return flight from Paris landed in Boston on Feb. 16. As the plane sat on the tarmac, she texted with Peshkin, trying to confirm how she should handle the package in customs.

At first, Petrova said, her reentry felt normal. At passport control, an officer examined the J-1 visa that Harvard had sponsored, identifying her as a biomedical researcher. The officer stamped her passport, admitting her to the country.

Then, a Border Patrol officer approached her and asked to search her suitcase. All she could think was that the embryo samples inside would be ruined; RNA degrades easily. She explained that she didn’t know the rules. The officer was polite, she recalled, and told her she would be allowed to leave.

Then a different officer came into the room, and the tone of the conversation changed, Petrova said. This officer asked detailed questions about the samples, Petrova’s work history and her travel in Europe. The official then informed Petrova that she was canceling her visa and asked her whether she was afraid to be deported to Russia.

“Yes, I am scared to go back to Russia,” she said, according to a Department of Homeland Security transcript provided by her lawyer. “I am afraid the Russian Federation will kill me for protesting against them.”

Petrova’s attorney, Greg Romanovsky, said that Customs and Border Protection had overreached its authority by canceling her visa. He acknowledged that she had violated customs regulations but said it was a minor offense, punishable by forfeiture and a fine.

A spokesperson for the DHS, asked why Petrova’s visa had been canceled, said that a canine inspection found petri dishes and vials of embryonic stem cells in her luggage without proper permits.

“The individual was lawfully detained after lying to federal officers about carrying biological substances into the country,” the spokesperson said. “Messages on her phone revealed she planned to smuggle the materials through customs without declaring them. She knowingly broke the law and took deliberate steps to evade it.”

Petrova became among the thousands of immigrants detained since Trump took office. She was sent to the Richwood Detention Center to await a hearing in which she will present her case for asylum to an immigration judge.

“If she wins, she will not be deported,” Romanovsky said. “If she loses, she will be deported to Russia.”

He has also filed a petition for her release in federal court, and pressed ICE to release her on parole. “I am basically pleading for mercy,” he said. “In a different environment, I think she would have been out a long time ago.”

The ordeal has challenged the view of America that Petrova formed in Russia. “This is not the kind of America I used to know,” she said.