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A man and woman walked out of a subway car at the 51st Street station in Manhattan and darted into the next one on the same train. A plainclothes police officer noticed.

It was rush hour on a Tuesday evening in September on the busy No. 6 line. The officer watched as the woman dipped her hand into a commuter’s purse while her partner stood in front of her, shielding her from view, according to the officer’s affidavit. The woman lifted out a wallet, and the officer and his partners closed in.

She threw the wallet to the ground, and the commuter quickly identified it as hers. The woman, Jenny Gomez Velandia, 27, and her accomplice, John Diaz-Albarracin, 31, were arrested, according to a criminal complaint. What seemed like a routine pickpocketing had been thwarted.

But the suspects were not routine. Unlike most pickpockets, they had no criminal history in New York City. They were not locals. They were from Colombia and had come to New York for the purpose of stealing wallets on subways, one of several international pickpocket rings to descend on the transit system in 2018, the police said.