Sorry for the delay in replying, some more directly relevant replies had higher priority.
There is of course no official memo, these people aren't that dumb, or rather know the MSM wouldn't get away with carrying their water if one came to light. But there's pretty clear testimony by a BATF whistle-blower of a supervisor's comments that laid it out. While I don't have much respect for anyone in the organization, the rank and file properly had drilled into them the principle that they weren't to let guns walk, it's a cardinal rule and a lot of them are very upset at what happened.
And it's clear to anyone capable of following a logical argument based on three undisputed facts about the Arizona operation (it looks likely there was also a Texas one, and we have some evidence for a Florida/Miami area one targeting Latin America below Mexico):
When gun stores called up the BATF about extremely suspicious buyers, it told them to allow the sales, around 2,000 guns in total.
Unlike the Bush era's Wide Receiver operation, which put radio transmitters in the stocks of rifles, no attempt whatsoever was made to follow the guns south of the boarder, including informing, let alone involving the Mexican government (they're not happy).
Top Cabinet level officials like Attorney General Eric Holder and Secretary of State Hillary Clinton, plus many figures on down, made statements about how American gun stores and shows were supplying Mexican drug cartels despite a paucity of evidence.
E.g. you can't buy grenades or post-1986 manufactured automatic weapons in those venues, and for the usual reasons not really including effectiveness they prefer full auto M16s (originally supplied to the Mexican government by the US) and AK-47s (generally available on the black market, and much less bulky than drugs) to more expensive semi-auto US civilian versions. It should go without saying that the Mexican government doesn't ask the US government to trace weapons stolen from their armories.