Officers in western Jalisco found "31 gold- and silver-plated handguns of varying caliber studded with diamonds and engraved with the name 'Lobo Valencia,'" the federal agency said in a statement.

The basement in Zapopan also yielded four rifles, 700 rounds of ammunition, 200 grams of marijuana, jewelry and documents bearing the name of Oscar Orlando Nava Valencia, the statement added.

Valencia is not on a list of 24 drug bosses sought by Mexican law enforcement, which offers $2.4 million reward, in total, for their capture. But he is the right-hand man of Joaquin Guzman, who tops the wanted list, the statement said.

US Secretary of State Hillary Clinton last year said Mexican drug cartels made $25 billion a year by smuggling drugs into the United States, but other experts believe the profits are much higher.