New Mexico State Police officer Gabriel Valdez became one of the most important and dedicated investigators of cattle mutilations through his decades-long investigation of cases on and around the Jicarilla Apache Indian Reservation near Dulce, New Mexico. Beginning in 1976, Valdez investigated dozens of mutilation reports in Rio Arriba County, meticulously documenting each case with photographs, measurements, and tissue samples. His reports described injuries that he believed were inconsistent with natural predation: precise excisions of organs, absence of blood, unidentified chemical residues on the animals' hides, and unusual fluorescent markings visible only under ultraviolet light. Valdez also documented helicopter activity, vehicle tracks from unidentified government-type vehicles, and what he described as gas canisters found near some carcasses.
His investigation led him to conclude that the mutilations were the work of a covert government operation, not extraterrestrial activity or conventional predation. Valdez's extensive case files, preserved after his death, represent one of the most detailed law enforcement archives on cattle mutilation and have been studied by researchers on all sides of the debate.