The premise was something out of a B-grade thriller. At 2 a.m. on Sunday, April 19, a car plunged into a ravine in Chihuahua, the sprawling Mexico state that borders Texas and New Mexico, killing four. According to the initial information, two of the deceased belonged to the State Investigation Agency (AEI in Spanish), while the other two were something else entirely.

In a tweet later that day, US Ambassador Ronald Johnson asserted that they were “US Embassy Personnel” without specifying further, while press reports identified them as “training officers,” an enigmatic label that only served to deepen the mystery. The five-vehicle convoy the car had been a part of was ostensibly returning from locating a remote drug lab in the Sierra Tarahumara Mountains, despite the fact that both the constitution and the terms of Mexico’s National Security Law of 2020 prohibit foreign agents from participating in any such operation on Mexican soil. What exactly then was going on?

At her morning press conference the following Monday, President Claudia Sheinbaum was unambiguous: the federal government had been unaware of the operation, whatever it was. Beginning with condolences for the deceased agents (despite later claims by right-wing media and Donald Trump press secretary Karoline Leavitt that she had omitted them), Sheinbaum confirmed that her government was seeking clarifications from both the embassy and the state government headed by the opposition National Action Party (PAN) politician Maru Campos.