Just north of the city of Zacatecas the smaller aircraft jogged farther east to avoid Guadalajara’s powerful air traffic and air defense radar system. Now the aircraft was no longer over the mountains but flying in Mexico’s central valley, so it was back down to five hundred feet or less aboveground, using terrain-avoidance radar, precise satellite-guided navigation, night vision devices that made it easy to see the ground and large obstacles, and photo-quality digital terrain and obstruction charts, with computerized audio and visual warnings of nearby radio towers and transmission lines. Northeast of the city of San Luis Potosí, the aircraft made a hard turn south to avoid Tampico’s coastal surveillance radar.
Now the aircraft was flying in the heart of Mexico’s population centers, with 80 percent of the country’s population within one hundred miles of their present position—and most of the country’s air defense, surveillance, and air traffic radars as well. Plus, they had very little terrain to hide in now. Staying far away from towns and highways, relying mostly on darkness to hide their presence, the aircraft’s crew prepared for the most dangerous part of the mission. After over five hours of relative peace and quiet, the last twelve minutes was going to be very busy indeed. The crew performed their “Before Enemy Defended Area Penetration” checklist, making sure all lights were off, radios were configured to avoid any accidental transmissions, the cabin was depressurized and secure, and the crew members waiting in the cargo area were alerted to prepare for evasive maneuvers and possible hostile action.
Somehow, after the events that had transpired in the past several days, it was not hard to imagine they were flying over enemy territory—even though they were flying over Mexico.
Immediately prior to the last turning point over the town of Ciudad Hidalgo, eighty miles northwest of Mexico City, came the first radio message on “GUARD,” the international emergency frequency, in English: “Unidentified aircraft at the two-niner-zero degree radial of Mexico City VOR, seventy-three DME, this is Mexico City Center, squawk Mode Three five-seven-one-seven; ident, and contact center on one-two-eight point three two, UHF three-two-seven point zero. Acknowledge immediately.” It was repeated several times in both English and Spanish, even after the radar return completely dropped off the scope.
The message was never answered, of course—which only served to alert the Fuerza Aerea Mexicana, the Mexican Air Force, and the Interior Defense Forces of the Ministry of Internal Affairs. The Mexican Air Force had one airbase northeast of Mexico City dedicated to air defense, with nine F-5E Tiger II fighters assigned there; two were on twenty-four-hour alert. By the time the aircraft was twenty miles west of Mexico City, the fighters were airborne. But the pilots had had very little actual night low-altitude air defense training, and the radars on the American-made Tiger IIs were not designed to detect low-flying aircraft against a heavily industrialized and populated background, so the fighters could do nothing else but fly a medium-altitude patrol pattern, away from the commercial airline arrival and departure paths and surrounding high terrain, and hope that Mexican air traffic control could spot the unidentified aircraft again and vector them in close enough for visual contact.
But the Internal Affairs Ministry’s response was far different. Primarily charged with identifying, tracking, and stopping insurgents and revolutionaries that might threaten the republic, the ministry responded to every such alert, no matter how small, as if it was an impending coup or attack on the capital.
The Political Police, which commanded a larger helicopter force than the army and air force combined, immediately launched several dozen helicopters of mixed varieties over the capital, mostly American-and Brazilian-made patrol helicopters that carried a flight crew of two, an observer/sniper in the rear, along with searchlights; a few were equipped with infrared cameras. The helicopters flew preplanned patrol routes over the capital, concentrating on scanning government buildings, embassies, and residences for any sign of trouble. Another dozen helicopters were placed on standby alert, ready to respond immediately if necessary; the Internal Affairs Ministry also could commandeer as many aircraft of any kind as it wanted, including helicopter and fixed-wing gunships and large transports. A small fleet of VIP helicopters was also placed in standby or prepositioned to various places around the capital, ready to whisk away high-ranking members of the government to secure locations.
At the same time, the twenty-five thousand members of the Federal District Police were put on full alert and ordered to report to their duty stations or emergency assignments. Within the Federal District, the Federal District Police had ultimate control, even over the military; they were just as well equipped as the armed forces, including armored personnel carriers, antitank weapons, attack helicopters, and even light tanks. These ground and air forces were deployed throughout the Federal District and immediately began closing off side streets, shutting down bars and restaurants, restricting citizens to their homes, and establishing strict movement control throughout the capital. The highest concentration of Federal District Police were at the Palacio Nacional, Zocalo, Embassy Row along the Paseo de la Reforma between the Mexican Stock Exchange and the Chapultepec Polanco district, the major hotels near the Independence Monument and Lincoln Park, and the Internal Affairs Ministry itself.
Mixed in with all these protective forces were the Political Police, whose primary job was to maintain surveillance on all of the important and high-ranking Mexican politicians, their families, and major associates—including their staffs, bank accounts, telephones, e-mails, and postal correspondence, unofficial as well as official; and the Sombras, the Special Investigations Squad, assigned to keep an eye on the highest-level persons in the Mexican government and report any suspicious activities directly to Felix Díaz. During these emergencies, every member of the Political Police was brought into the ministry headquarters at the Bosque de Chapultepec and ordered to update their contact files and begin careful monitoring of their assigned targets to discover any clues of possible conspiracies against the government.
Located in the south-central edge of Chapultepec Park just south of the zoo and west of Castillo de Chapultepec, the Ministry of Internal Affairs complex was in effect a walled fortress—unlike most government buildings in Mexico City, citizens were not permitted to freely come and go, and there were no tours. A series of Napoleonic-style office buildings surrounded the complex, creating the outer wall of the complex, with Federal District Police armed with automatic weapons stationed on the rooftops. On each side, the buildings were connected by Spanish-style arches with ornate iron gates. The gates looked decorative, but they had been stressed to stop a five-ton truck from crashing through them, and the width of the opening had been purposely reduced to less than that of an armored personnel carrier.
Inside the outer walls formed by the older office buildings were the ministry’s operations buildings—the investigator’s offices, communications, arsenal, and barracks, housed in three plain-looking rectangular boxlike buildings arrayed in a triangular shape radiating out from the center of the complex. In the center of the triangle was the main ministry building, a Stalinist-era-looking eight-story tower, resembling simple blocks progressively smaller in size stacked atop one another, topped with a tall antenna housing structure that supported hundreds of antennas of all sizes and kinds. The building not only housed the minister’s offices and those of his extensive bureaucratic staff but also the electronic eavesdropping and computer centers, the intelligence analyst’s offices, the extensive prison complex, the offices of the Political Police and Sombras, and a so-called special medical center in the subfloor areas—the interrogation center.