In 1907, an American detective by the name of Thomas Furlong was employed by Enrique Creel, at that time governor of Chihuahua, to locate Mexican dissidents in the U.S. The American headquarters of the PLM was in St. Louis at that time. There were a large number of expatriates who knew of its whereabouts and as a result, Furlong had no difficulty locating the dissidents in the city. Magón, however, was living in great secrecy in Los Angeles. He used a pseudonym, and only two other persons in the city knew his real identity. If they needed to see him, they did so between midnight and dawn. The dissidents in St. Louis soon became aware that they were being sought by agents working for the Mexican government. Librado Rivera left the city in order to evade capture and although he was constantly on alert for agents who might be shadowing him, he failed to elude them. He was followed to Los Angeles and to Magón's place of residence. Furlong kept the house under surveillance for some time. Finally, on August 23, 1907, Magón, Rivera and Antonio Villarreal were taken into custody by Furlong, two of his assistants and some officers from the Los Angeles police department.