Mexican drug cartels, the abominations that sprang from the environment of Prohibition, probably executed the 8-member Ohio family. A large marijuana-growing operation was found on their property. Either to protect their black market turf or out of some other vendetta, the reasons come from the Drug War. The Drug War gave life to the murderous cartels by creating an environment where only violent criminals buy and sell marijuana, cocaine, meth, or the myriad other prohibited substances. This is how a black market operates, this will always happen as long as governments of the world insist on enforcing Prohibition. The drug cartels would disappear if drugs were legalized in the US. By enforcing the Drug War at home, the US government is creating an optimal environment for the invasion of these foreign cartels, who know how to handle the feds.
Prohibition is societal poison, it incentivizes criminal behavior on both sides of the law, destroys families, lives, liberties, and consumes taxpayer billions that are wasted all for an endeavor that is worse than futile.