I have read reports and heard interviews about the ACLU shadowing the Minutemen watching for "civil rights violations". I'll do some checking and post links I find. This whole thing reeks of set-up.
I've heard those reports too. ACLU/leftist types may be passing the MM locations on to the Mexican consuls in LA and elsewhere who in turn pass it to their bosses in Mexico. The USBP has deniability but their upper echelons are probably not unhappy with whoever is passing the info to the Mexicans.