It had been a great week with family on the sunny beaches of Cancun, Mexico, but Jemmy Jimenez Rosa and her family were ready to be home in Canton.

Then, shortly after they landed at Logan Airport in Boston, she was whisked off to a back room, where US Customs and Border Protection agents posed a jarring question: “Tell us about the arrest.”

She had entered a guilty plea to a charge of possession of a bag of marijuana more than two decades ago. She was later pardoned.

Still, the long-ago offense has now upended the lives of the 42-year-old native of Peru, who is a legal US resident, and her family.

Her husband and lawyer say she was detained for 10 days, first at the airport and then in Maine, as authorities provided scant information to her panicked family.

It was only after her la

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