Steve: my weapon-of-choice is Google. Do you know if the Yahoo! contributor piece pre-dates 3/16 at around 11 p.m.??
I had a feeling that this is all a bunch of journalists copying and pasting from one another, which makes me sad and slightly depressed (as a former student journalist and journalism major when I was in college).
At any rate, the biggest tip-off that something is amiss is when journalists don't name their sources.
This happened multiple times as I see it:
* Brendan Missett (who as I see is the first in time, although perhaps Yahoo! beat him) has a story with literally no attribution. It looks like somebody copied a press release verbatim.
* Hugo Albert Velasco (of Notimex?) tweets a photo, it's not clear he actually was the person who took it (there's really not a whole lot of description but then again, you know, Twitter's 140 character limit sort of deters that). Any case, it's odd that his employer doesn't seem to be the one all over this story, don't you think?
* El Universal and the other Mexican media seem to be repeating Missett with spotty attribution. Not clear if they did any independent verification and if so, how much.
* AFP seems to be repeating what the Mexican media said.
* Everyone else attributes it to AFP.
Very, very murky.
Now to be sure, I must admit that I have no idea where the First Daughter is right now. I can't prove to you she's not in Oaxaca.
But the provenance of all these news stories must make one wonder, and my guess is that we have a lot of journalists who aren't really doing good journalism, and it's quite possible, as I stated earlier (perhaps a bit too confidently, although I still suspect) this could very well be a Republican dirty trick, and you've got inexperienced or incompetent journos aiding and abetting them.
"Malia Ann Obama, daughter of U.S. President Barack Obama, arrived on a commercial flight to Oaxaca for a private tour on the evening of Friday March 16th.
Surrounded by a security team, Malia Obama arrived at the headquarters of the commercial airport in the capital to join a group of twelve young teenagers from a United Airlines commercial airliner departed from Houston, Texas.
Official information states that President Barack and First Lady Michelle Obama's oldest daughter, who is thirteen, has an escort of twenty-five agents composed of marines and members of the Secret Service. All will wear black suits and use radio communication.
Private security escorted Malia Obama in three armored trucks to Hotel Camino Real, located in Oaxaca's Historic Central District.
According to her leaked agenda, during the weekend Malia will visit the "El Arbol del Tule," the archaeological site of Monte Alban, and the towns of San Martin Tilcajete, the site of many local handicrafts, and San Bartolo Coyotepec, in addition to the main attractions in the city of Oaxaca.
Malia's is one of two Obama children. Her sister, Sasha, is 10 years old."
The earliest references to Malia (supposedly) being in Mexico in a reputable source come from the online site of a Mexican newspaper, El Universal.