Washington ? It was a very stupid thing to do, Kathryn Ingleson says now. She was a teenage cashier, and she used customers’ credit card numbers to buy $339.07 worth of items, including a fake Christmas tree. She pleaded guilty, got probation and pretty much forgot about it.

Until, that is, she took a trip abroad six years later and federal authorities decided the crimes made her deportable. Now the British citizen, who has lived in Newport News, Va., as a lawful permanent resident since she was 7, has been ordered to leave the United States this month.

“It’s just like a nightmare, really,” said Ingleson, 31, who has worked at a packaging company for a decade and has two children, both U.S. citizens.

Lawyers and activists said Ingleson is one of a rising number of legal immigrants with relatively old and minor criminal records to be snagged in the federal government’s stepped-up efforts to deport those whom authorities refer to as “criminal aliens.” Unlike illegal immigrants captured in raids or while crossing the border, lawyers said, these legal immigrants are often people who believed they had paid their dues, only to be flagged while presenting green cards at customs checkpoints or applying for visa renewals or citizenship.

A 1996 federal immigration law facilitated such deportations by greatly expanding the categories of crimes that are deportable offenses, including some misdemeanors. The law also removed most legal immigrants’ rights to fight expulsion by presenting evidence of community ties or hardship to U.S. citizen relatives, and it was retroactive, so that even those convicted before the law took effect in 1997 can be deported.