Ok take tinfoil off potatoes in BBQ and place on head.

1) Follow the money $90 billion to the US
2) Motivation money, political spin etc
3) Means: As stated in the above post the US has informants in the Mexican drug cartels heck double layer tin hat time they probably run some of them. Consider the border guards who make a lot of money smuggling and the ATF running guns to the cartels it is not impossible.

So motivation money & means. Also the prosecution doesn't even have to be successful. It just has to grab headlines until the deal is sealed

The question you got to ask yourself what would you do for $90,000,000,000.00?
Well do you feel lucky?