A former Mexican police officer, known as a symbol of the fight against drug cartels after emerging as the lone survivor of a 2015 attack on a military helicopter, died in an ambush April 30.

An SUV bumped a black truck driven by Iván Morales Corrales, 43. Gunmen hopped out and fired more than a dozen shots, killing Morales and an unidentified woman in the state of Morelos, a 2.5-hour drive south of Mexico City, according to two retired U.S. drug agents and multiple Mexican media outlets. It’s unclear who killed the victims or why. The case remains under investigation.

The killings in the city of Temixco – typically a peaceful place – came during the 10th anniversary week of the downing of the helicopter, blamed on Cártel Jalisco Nueva Generación, known as CJNG. The cartel is one of the most militant in Mexico, turning territories they control into warzones through use of rudimentary tanks, roadside bombs and disappearances.