He ended his career by appearing in four low-budget Mexican horror films: "Isle of the Snake People," "The Incredible Invasion," "Fear Chamber" and "House of Evil." This was a package deal with Mexican producer Luis Enrique Vergara. Karloff's scenes were directed by Jack Hill and shot back-to-back in Los Angeles in the spring of 1968. The films were then completed in Mexico. All four were released posthumously, with the last, "The Incredible Invasion," not released until 1971, two years after Karloff's death. "Cauldron of Blood," shot in Spain in 1967 and co-starring Viveca Lindfors, was also released after Karloff's death.