that was a common rumor in the 70s about latin america, these films never existed. i don't think any true "snuff film" has ever been known, people thought peter scully made it but it turned out the deaths he caused were not parts of his quirky videos
there was a 1976 film called "snuff" that gave a signal boost to these rumors by pretending to actually be one (it's just a crappy slasher film from a few years ago with an extra scene added at the end.) cannibal holocaust then gave an even bigger boost by pretending to be real and eventually having to prove in court that it was fake, and while that wasn't in latin america, it was in a dirt poor 3rd world country. latin america was still the aim of the rumors