American filibusters and Mexican sympathizers were active all along the Mexican American border area, from north of Laredo to Brownsville long before the Plan of San Diego came to light. This activity was being investigated by American authorities, especially the Bureau of Investigation.
On Jan. 19, 1915, a few days before Basilio Ramos was arrested in McAllen by Hidalgo County law enforcement officers, Bureau Agent F. J. McDevitt reported that a pact had been made by Villa and Huerta supporters in the Valley to join their efforts and resources to fight Carranza across the river. Villa and Huerta sympathizers were numerous, well armed and well financed. McDevitt reported that forays across the Rio Grande were common and that they were, moreover, condoned and supported by local law enforcement officials along border towns.
The protection of local law enforcement was especially true in McAllen, which appeared to be the headquarters for the Villa-Huerta junta. Dr. Andres Villarreal and local merchant Deodoro Guerra were the leaders of this effort. These were the same two men who were responsible for the arrest of Ramos and the discovery of the Plan of San Diego. Although, many scholars have suggested Ramos was a Huertista, this suggests that he may have in fact been a Carranza sympathizer. Villarreal and Guerra were Villa supporters and at that time appeared to be in cahoots with Huertistas and would have taken in a fellow sympathizer, but would have turned on someone they viewed as supporting Carranza.
Arms and ammunition for Villa supporters in Mexico, McDevitt reported, were regularly shipped from Guerra’s hardware store.
“They have an active and effective secret service system and do not hesitate to kill to preserve their organization and their ‘concentration camps’,” McDevitt said in a report to Bureau headquarters.
The agent supported his statement with the account of one “Elloy” believed to be a Carranza spy who was detained by McAllen City Marshal Everett Anglin and later “disappeared.”
McDevitt continued in his report that the Villa-Huerta cabal in McAllen also controlled the telegraph and telephone systems giving them inside information on the movements of U.S. Troops and Texas Rangers and thus stifling their efforts at curbing activities of filibusters and Mexican revolutionary activists.
The Villa-Huerta network would secure “grubbing” contracts and use the land to assemble recruits for their Mexican revolutionary efforts. If anyone questioned who they were, they replied they were “poor Mexican refugees trying to make a living.” On one occasion, Army troops stopped four cars loaded with arms and ammunition and one “white driver got all shot up.” Marshall Anglin replied to the Army officer telling him about the incident, “hell that was my car and Tom Mayfield” (an Hidalgo County deputy sheriff).
McDevitt recommended that the Bureau secure a couple of Mexican informants in McAllen and have one of their own agents infiltrate the group pretending to be a cowboy or rancher.