Patrick Campbell, 33, of Sierra Leone, was the target of a setup by the Department of Homeland Security which involved posing as agents of the Iranian government, looking to buy massive amounts of uranium. Campbell identified himself as an employee of a mining operation, who could get the requested materials to the buyer (in this case, a Homeland Security agent).
After a back-and-forth where agents grew skeptical that Campbell would actually be able to get the enriched uranium known as "yellowcake," Campbell finally secured a visa to come to the United States to complete the sale. The sale had to be done in the United States so Campbell could be charged with breaking the United States' embargo on exporting goods from the U.S. to Iran.
Campbell also reportedly told the agent that he had previously sold uranium “to agencies in China and Ecuador,” while trying to convince the agent he was a viable seller. Authorities do not believe the samples hidden in his shoes were actually uranium, however.