The development sparked a particular concern among the Mexican authorities since the stolen device contains a highly radioactive source of Iridium-192. If removed from a special secure container, this source could inflict “permanent injuries” to anyone who has direct contact with it for mere minutes, the government statement warns.

It is unclear if the device was the robbers’ target or whether they were aware of its existence at all. The device, described as a gamma-ray source projector, was produced by an American company, QSA Global, which specializes in supplying “high performance radiation sources used in non-destructive test devices, oil well logging (OWL), industrial processes, and medical research.”