This story from the WSJ claims that
the extradition of Joaquín “El Chapo” Guzmán, Mexico’s long-dominant drug lord, has led to an explosion of violence in his home state of Sinaloa, the birthplace of the country’s narcotics industry.
Rival factions are fighting over Mr. Guzmán’s billion-dollar empire as he awaits trial in solitary confinement inside a high-security prison in New York. He was extradited to the U.S. in January on drug-trafficking and murder charges.
This explanation for increased violence in Mexico is exactly what one would predict from this Cato Research Brief, by economists Jason Lindo and Maria Padilla-Romo:
We find that the capture of a [Drug Trafficking Organization] (DTO) leader in a municipality increases its homicide rate by 80 percent, and this effect persists for at least 12 months. Consistent with the notion that the kingpin strategy destabilizes an organization, we also find that these captures significantly increase homicides in other municipalities with the same DTO presence. In particular, we find that homicide rates in neighboring municipalities with the same DTO presence rise 30 percent in the six months after a kingpin capture before returning to expected levels. Further, kingpin captures cause homicide rates to grow over time (to 18 percent above expected levels 12 or more months after a capture) for more-distant municipalities with the same DTO presence. We find little evidence of increased homicide in neighboring municipalities where the captured leader’s DTO did not have a presence.
Disputes between rival suppliers occur in all industries; but in legal ones, the disputes take the form of advertising wars and lawsuits, not violence. See also this old paper of mine on the same subject.