Unknown to the Comandante, scientist Don Panchito is responsible for the murders and has been murdering the athletic community in order to provide test subjects for his experiments; Panchito's procedure involves removing the victim's brain and replacing it with that of an animal's in an effort to find a way to conquer death.

Unlike many of Panchito's other victims, Santana survives the procedure but as a result is transformed into a grotesque and bestial state that seems to have taken on several characteristics of that of an ape.

However, during the fight Santana's animal side takes over and overrides Panchito's programming, ripping off his mask and exposing his hideously deformed face.

The story for Ladrón de Cadáveres was partially inspired by Universal's Frankenstein[1] which was a commercial and critical success.

Hoping to replicate this success, Mexican directors responded by releasing their own variations of Universal Studios famous monster movies, but differed enough to avoid any copyright lawsuits.