K. Gordon Murray wasn't the only producer making a mess of Mexican movies: Jerry Warren was guilty of the same, his film Creature of the Walking Dead starting life as La marca del muerto by director Fernando Cortés. Enterprising Warren re-edited the film, added new footage, dubbed it into English and added clumsy exposition via narration.
Fernando Casanova plays Dr. Malthus, who discovers the laboratory and scientific notes that belonged to his grandfather, who was hanged for the abduction and murder of young women whose blood he used in experiments, his goal being eternal youth. Following the notes, Malthus proceeds to revive his dead grandfather, but a continuous supply of fresh blood is required to keep him alive...
I've no idea how good or bad the original Mexican movie was before Warren got his mitts on it (I suspect it wasn't great), but Creature of the Walking Dead is awful: the additional footage of random people gabbing about who knows what doesn't sit well with the original scenes, the editing is choppy, the pacing is slow and tedious, the narration is terrible, and there is repetitive use of the same few bars of music throughout the entire movie which proves extremely grating.
2.5/10, rounded up to 3 for the ridiculous equipment in the lab, which comprises of a big machine with lights and a large dial, a few bottles and tubes full of liquid, and a spinny thing.