I'll leave the determination of believeability to you. If it's not true, no harm done. If it IS true....OMFG! Be sure to follow the links embedded within the article, too. Personally, knowing of ATF's other "transgressions", I have no problem believing this as presented.
http://www.ncc-1776.org/tle2011/tle602-20110109-03.html
We now know, however, that the flow of weapons to the south is indeed, in part, coming from within the United States, not from dealers or their civilian customers, but specifically from the BATFE, which has been caught "walking" weaponsrecently five hundred semiautomatic AR-15 riflesacross the border into Mexico in order to "boost" the statistics they have been using to try to limit our rights.
http://www.ncc-1776.org/tle2011/tle602-20110109-03.html