Her attorneys had challenged the criminal prosecution, arguing that the charges were vindictive and had been filed only after it appeared Petrova would prevail in her immigration case.
Prosecutors’ decision to drop the charges ended the criminal case even as questions about the detention of noncitizen researchers remained part of a broader pattern cited by her legal team.
The case had combined an immigration fight with a rare criminal filing over scientific samples that her lawyers described as posing no threat.
US prosecutors dropped criminal charges against scientist Ms Petrova after she was detained over frog embryos she carried for medical research.
Petrova is among numerous noncitizen academics who have been arrested or threatened with deportation by the Trump administration.
Customs officials questioned Petrova about the samples when she arrived at Logan International Airport.
Following the dismissal, Petrova’s attorney Daniel Marx criticized the decision to pursue criminal charges against the scientist.
They maintained that criminal prosecutions involving conduct like hers were uncommon.