Nemesio “El Mencho” Oseguera Cervantes was a feared Mexican drug lord and the leader of a ruthless cartel accused of masterminding efforts to push fentanyl into the United States.

The killing of Nemesio “El Mencho” Oseguera Cervantes triggered unrest in 20 of Mexico’s 32 states, with suspected gang members torching buses and businesses, blocking roads and clashing with securit...

Nemesio Oseguera, the 59-year-old leader of the Jalisco New Generation Cartel, was injured in a clash with soldiers in the town of Tapalpa and died while being flown to Mexico City, the army said in a...