A man who tried to smuggle heroin into the United States concealed in his rectum was caught by U.S. officials - with the help of a drug-sniffer dog - as he walked across the border from Mexico, Reuters reported. Paulo Alfredo Macias, 35, was being held in the El Paso County Jail without bond after being caught on Monday at the Paso Del Norte pedestrian crossing with nearly 5 ounces of heroin. "Internal body carriers are not common at land border ports of entry so this is a significant seizure," the official statement said.