An abandoned ranch in western Mexico that groups searching for missing relatives had claimed was an “extermination camp” — because of discarded personal items and burned remains found there — was a training hub for a major cartel, Mexico’s attorney…

An abandoned ranch in western Mexico that groups searching for missing relatives had claimed was an “extermination camp” — because of discarded personal items and burned remains found there — was a training hub for a major cartel, Mexico’s attorney…