There's no evidence of that, but there's plenty of evidence of the gun control angle. Starting with both Obama and Hillary holding joint press conferences with their Mexican counterparts to publicize fake "traced guns" statistic and call for new gun control, and up to and including the Obama ATF order on sales of multiple assault weapons in border states.
What more control could you get?
If it was about gun control they wouldn't be letting grenades walk.
I find it a little hard to believe they would destabilize the Mexican Govt. on the hope of getting gun control legislation passed. A destabilized Mexico works against their argument for more gun control. The more violence there is in Mexico the more people that never thought of owning a gun are buying guns.
If it's about gun control it's not gun control through the legislative process, it would be through an executive order. For that to happen all hell would have to break loose on this side of the border. That would mean gun control isn't the ultimate objective, absolute power is the objective.