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Go Nakamura, a freelance photographer whose work has appeared in The New York Times and who was on the list, said he had suspected for several months that his name had been flagged to immigration officials.

In an interview Thursday, he recalled being stopped by Mexican authorities in late December while he was near the border fence in Tijuana to take photographs of migrants. The officers asked to see Mr. Nakamura’s passport, something he had not experienced during other lengthy assignments on the border, he said. He thought it was strange when the officers took photos of his passport on cellphones.

Mr. Nakamura, an American citizen, tried to re-enter the United States several days later, and initially faced routine questions. He was asked about his background, where he lived, where he went to school. He was also asked about when he began working as a photojournalist.

But the questioning began to alarm Mr. Nakamura when an officer pulled out a document with pictures of about 10 to 14 faces and asked him to identify them.

“They asked me if I recognized any of the faces,” Mr. Nakamura said. “I didn’t, so I said no. The officer who showed me the papers, she was asking me if I was connected with the organizers of the caravan. She was like, have you met the organizers or do I know the organizers?”

“I felt like they thought I was a spy or something,” Mr. Nakamura said.

Kitra Cahana, a freelance photographer on the list whose work has also appeared in The Times, said she was barred from entering Mexico on Jan. 17 while she was en route to photograph another caravan of migrants traveling through the country. As she was about to board a flight from Montreal to Detroit, she scanned her passport at a pre-clearance machine, which printed out a picture with an “X over my face.” She was taken into secondary questioning in Montreal, but was ultimately allowed to board her flight.