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Editor's note: Ruben Navarrette is a CNN contributor and a nationally syndicated columnist with the Washington Post Writers Group. Follow him on Twitter: @rubennavarrette.

(CNN) -- I keep thinking of those television ads from the Mexican tourism industry urging Americans to "Come visit Mexico."

Visiting isn't difficult. For some Americans, it's leaving that's the problem.

For years, U.S. officials have urged their Mexican counterparts to get tough on drug traffickers. The Americans even provided $1.4 billion through the Merida Initiative to help our friends south of the border accomplish that goal.

Yet, the drama unfolding in the state of Sonora -- just across the border from Arizona -- can't be what U.S. officials had in mind.

The idea was to help Mexico's police and military pursue violent criminals -- the sort who terrorize people by scattering human heads like party favors on the dance floors of nightclubs -- not to prey on Americans held for ransom by crooked cops looking for their next payday.

And that's what appears to be driving the story of Yanira Maldonado, a 42-year-old U.S. citizen who sits in a women's prison in Nogales, Mexico, on what seem to be bogus drug charges. Maldonado -- who is Mormon, and has seven children, and two grandchildren -- is represented by a Mexican attorney. We don't know for sure what happened. But if Yanira is innocent of these charges, which is the most likely scenario given that the Mexican authorities have no evidence of her guilt, she must be released immediately.

Meanwhile, the U.S. State Department is monitoring the situation and providing the family with updates.

Yanira Maldonado speaks out from jail

Was mom jailed in Mexico framed?

The family's nightmare began last week when the Mexican-born Yanira and her husband, Gary, boarded a bus to head back to the United States after attending her aunt's funeral in Mexico.

That was their first mistake. Those of us who visit Mexico know you never get on a bus. It makes you easy pickings for bandits and bad cops, and sometimes you can't tell the difference. Bandits might take your money, and let you go on your way. Bad cops take your liberty, and hold it until someone back home sends enough money to let you go on your way.

Either way, it's not personal. It's just a business transaction. But it's a cruel and ugly business.

Anyway, back to the bus. It came up to a military checkpoint -- which might as well be a toll booth -- and everyone was taken off the bus as soldiers boarded it.

"I was at the checkpoint, asked to get off bus," Yanira told CNN from prison. "They were checking for drugs and I don't know what else. They say they found something under the seat but I never saw anything. They didn't show me anything. It was amazing all what they did."

The soldiers claim that they found a package containing 12.5 pounds (5.7 kilograms) of what appeared to be marijuana under Yanira's seat. And so they placed her under arrest, and handed the case over to the Mexican attorney general's office for prosecution.

Maybe the authorities are telling the truth. Or maybe the drugs were there before she ever sat down. Or maybe the soldiers put the drugs there. Or maybe there were no drugs. No one knows, because, conveniently, the only people on the bus were the soldiers.

Whatever happened, it seems unlikely that a woman could have carried a package weighing over 12 pounds onto a bus and slipped it under her seat without being noticed.

Gary Maldonado has said that he and his wife checked their bags, and boarded with no luggage.

He also says that when his wife was taken into custody, one of the soldiers told him matter-of-factly that it would cost him $5,000 to get her released. Later, according to family members, he was quoted the same price by civilian authorities -- $5,000 -- for her release, whether she was found guilty or not.

That's how it works. Think of it as a processing fee.

In Mexico, stories like this one -- which are all about money, and corruption, and how predatory some hungry people can be when they catch a glimpse of a piece of bread -- are as common as pinatas and margaritas.

But that's not supposed to be the case anymore.

I was in Mexico City in November on a mission sponsored by the American Jewish Committee. We met with top officials, including President Enrique Pena Nieto, and the message could not have been clearer. "With a booming economy, less crime in metropolitan areas, and the reins of power now back in the hands of the Institutional Revolutionary Party, the country is open for business. This is the new Mexico."

Sorry folks, it seems there are still unseemly remnants of the old Mexico, and they are threatening to undermine the makeover.

The Maldonados probably aren't thinking about the relationship between the United States and Mexico at the moment. They just want a wife and mother to come home to her family.

With luck, Yanira Maldonado will be released on Friday. Her family will pay the fee as ordered, and she will be free to go. And this ugly chapter, in their lives and in the U.S.-Mexico relationship, will be closed.

But if that doesn't happen, on Saturday, Pena Nieto needs to intervene. And if he concludes that Yanira is innocent, he needs to order her release. And if he doesn't, Secretary of State John Kerry needs to fly to Nogales and wait there until he does.

Incidentally, Mexico is still waiting on the last few hundred million dollars in drug fighting funds promised under the Merida Initiative.

Congress should send the rest of the money. Minus $5,000. That should go to the Maldonado family, if and when Yanira is found innocent. Think of it as a processing fee.

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The opinions expressed in this commentary are solely those of Ruben Navarrette.