Ow did the Zeta drug cartel help explain a historical or current trend in Mexican Politics

The prompt:

Choose a topic that explains historical or current trends in Mexican politics. It is easier to identify a trend when visible change happens.
a. Length: 14 pages (not including annexes)
b. Double-spaced
c. 12 font
d. Divide the paper into clearly distinguishable parts: introduction, sections, conclusion, references (and annexes, if necessary). Use titles and subtitles.
e. Number the pages.
f. Use a Manual of Style (Chicago or APA, for example).
g. Quote sources (always; do not copy).
h. Must use mainly scholarly sources (books and articles), internet sources only if necessary. The paper must be original work. 2 points a day will be deducted if paper is turned in late.
Avoid being descriptive. Try to explain causes of regime change.