ASSUMING IT IS ACCURATE, FOX NEWS HAS DONE A FIRST-CLASS REPORTING JOB ON A HIGHLY CHARGED ISSUE - AT 1:18 P.M. ET:  Please read.  This is fascinating:

You've heard this shocking "fact" before -- ...90 percent of the weapons used to commit crimes in Mexico come from the United States...

...There's just one problem with the 90 percent "statistic" and it's a big one:

It's just not true.

In fact, it's not even close. By all accounts, it's probably around 17 percent.

What's true, an ATF spokeswoman told FOXNews.com, in a clarification of the statistic used by her own agency's assistant director, "is that over 90 percent of the traced firearms originate from the U.S."

But a large percentage of the guns recovered in Mexico do not get sent back to the U.S. for tracing, because it is obvious from their markings that they do not come from the U.S.

"Not every weapon seized in Mexico has a serial number on it that would make it traceable, and the U.S. effort to trace weapons really only extends to weapons that have been in the U.S. market," Matt Allen, special agent of U.S. Immigration and Customs Enforcement (ICE), told FOX News.

COMMENT:  This is a classic case of a statistic that gets picked up, is flashed around the world, and goes unchallenged, until an enterprising reporter starts asking tough questions.  A great example of good journalism, still being practiced.

April 2, 2009