PITTSBURG — At least two people are facing federal charges related to allegedly trafficking methamphetamine into the Bay Area from Mexico after federal authorities seized a horse saddle that had been packed full of the drug.

The investigation started after federal agents intercepted a package heading to Pittsburg, with a return address in Guadalajara, Mexico. Inside the package, there was a saddle, but when federal investigators took apart the saddle, they found the meth hidden inside, according to a federal affidavit.

So FBI agents came up with a plan: They replicated the package and the saddle, and sent an undercover agent disguised as a UPS driver to deliver it to a home on the 1100 block of Maple Street in Pittsburg. Then they surveilled the home and followed its occupants as they delivered the package to a woman named Mariela Solis.

Solis was then seen taking the package to another man, identified as Victor Galaviz, who paid her $500, according to the federal affidavit. That’s when police swooped in, arresting Solis, Galaviz, and a third man who has not yet been charged.

Solis and Galaviz were charged with conspiracy to distribute methamphetamine. They face up to 20 years in prison and a $1 million fine if convicted.

Authorities interviewed several people allegedly part of the conspiracy. One of them refused to provide the name of the person who ordered the package, saying that person “is part of the mafia and cartel,” and that he feared retribution, court records show.

In recent weeks, federal authorities investigating methamphetamine trafficking have turned their attention to Contra Costa County. They’ve busted several seemingly unrelated alleged meth-trafficking operations, seized several pounds of the drug, and filed conspiracy charges against at least four other alleged traffickers, according to court records.