Bing Guan, a freelance journalist from New York and student at the International Center of Photography, said he and a colleague were stopped by U.S. agents while returning from Tijuana in December. A plainclothes agent who didn't identify his agency showed Guan a multi-page document with dozens of photos and asked him to identify people in the images. The agent then asked Guan to show him the photos he had taken in Tijuana.