Kseniia Petrova, a Harvard scientist who was arrested last month on a federal smuggling charge, was released Wednesday from federal custody following a detention hearing in Boston.

Petrova, a Russian citizen, was taken into custody in May after prosecutors in Massachusetts accused her of smuggling frog embryos into the United States without properly declaring them.

She was released Thursday on conditions agreed to by both sides. A probable cause hearing on the smuggling charge is tentatively set for June 18.

Petrova had been in custody since February, when her visa was revoked at Boston Logan International Airport.

“I just want to thank everybody,” Petrova said outside the federal courthouse in Boston after her release. She said letters and messages from supporters helped her feel less alone while in custody. “It was a huge support without which I won’t be able to survive,” she said.

Initially held in a Vermont facility, she was transferred to a Louisiana immigration detention center, where she filed a petition arguing that her detention was unlawful and that she feared persecution if returned to Russia because she had participated in protests against the war in Ukraine. She was moved to federal criminal custody in May after being charged with smuggling.

At the time of her arrest, Petrova was working at a Harvard lab, where she had developed computer scripts to analyze images from a microscope that scientists say could transform cancer detection. Her colleagues told NBC News that she was the only person on the team with the rare combination of skills needed to interpret the data. “That was only her. It was only her,” Leon Peshkin, her mentor and a principal research scientist at Harvard, previously said.

Petrova described being confused and isolated after her arrest, saying she was held in a cell without contact with her lawyer or colleagues. “Nobody knew what was happening to me,” she said. “I didn’t have any contact, not to my lawyer, not to Leon, not to anybody.”

In late May, a federal judge in Vermont ordered her release from immigration custody citing concerns about the legal basis for her visa revocation and extended detention. She faces another immigration court hearing in July.

—NBC