The Tax Authority said the cash was found Monday after gamma-ray scans showed unusual shapes inside a shipment of home furnishings at Mexico City's international airport. A sniffer dog confirmed something was odd about the shipment, it said.
Inspectors found layers of US bills in denominations as low as $20 wrapped in plastic and coated with a powder that smelled of sulfur, and then covered by foam and the backing of the mattress pads. There were also layers of bills in the walls of the cabinets.
There was no immediate information on the owner of the shipment. Drug cartels frequently ship large amounts of cash back to South America to pay for drugs.
The Tax Authority, which is responsible for customs, says inspections have been beefed up to protect national security.
Also Tuesday, police in the central city of Cuernavaca said a female bodyguard for a top city police official was killed in an attack by gunmen late Monday. Assistant police director Jose Luis Aragon was unharmed.
The navy reported its forces freed 17 kidnapped people in a raid on two houses in the border city of Matamoros, in northern Tamaulipas state. The navy said the kidnappers had called the victims' relatives — almost all in the United States — and demanded money.
Acting on intelligence indicating people were being held at one of the homes, navy personnel raided the site and found a man who was apparently guarding the kidnap victims.
That raid led them to a second home, which was also apparently being used as a safe-house by the kidnapping gang.
A total of 17 people — 14 Mexicans, two Guatemalans and a Honduran — were freed. Drug gangs in northern Mexico frequently prey on migrants, kidnapping them to make their relatives pay ransom.
In the Pacific coast state of Guerrero, police reported Tuesday that the decapitated bodies of three men — one a local policeman — were found on a dirt road near the border with Oaxaca state. The other two victims were identified as a local mason and a barber.
Federal prosecutors in Guerrero said that they had brought drug, organized crime and weapons charges against Rogaciano Alba, a rural strongman who allegedly worked with both the Sinaloa and La Familia drug cartels.
The Attorney General's Office said Alba was caught with methamphetamine and an assault rifle in a car near the western city of Guadalajara in February. He has been held pending charges.
