MIAMI — Norma Borgoño immigrated to the United States from Peru in 1989. A single mother with two children, she set roots in the Miami suburbs, finding work as a secretary, dedicating herself to her church and, earlier this year, welcoming her first grandchild, a girl named Isabel, after Ms. Borgoño’s middle name.

She took the oath of citizenship in 2007, a step she felt would secure her status in her adopted homeland. But hers, it turns out, is not a feel-good immigrant story: The Justice Department has moved to revoke Ms. Borgoño’s citizenship, an action that could eventually force her to return to Peru.

Federal prosecutors in May filed a rare denaturalization case against Ms. Borgoño, 64, accusing her of committing fraud when she applied for citizenship and failed to disclose that she had taken part in a crime several years before she applied for citizenship — though she had not at the time been charged with it. It wasn’t until four years later, in 2011, that Ms. Borgoño pleaded guilty to helping her boss, to no benefit of her own, defraud the Export-Import Bank of the United States of $24 million.

Since President Trump took office, the number of denaturalization cases has been growing, part of a campaign of aggressive immigration enforcement that now promises to include even the most protected class of legal immigrants: naturalized citizens.