is a brilliant research scientist working for an atomic energy plant. It was his job to study a newly developed radioactive isotope. During an experiment he was exposed to the substance for a period of five-six minutes knocking him unconscious. He is brought to a hospital but doctors somehow found him to be completely healthy. However during observation when he was exposed to sunlight he transformed into a bestial reptillian man. It is concluded by his physician, Dr. Stern, that the unique radiation activated and evolved the dormant genes of human’s reptilian ancestors. These genes cause the rapid generation of scales over his entire body, two small horns just above his brow, and large pointed fangs in place of teeth. In addition he is granted tremendous strength allowing him to effortlessly overpower the average man. The cost of this strength however is his limited intellect and uncontrollable rage. The doctor also deduces that the catalyst of this transformation was sunlight as it was only after several minutes of exposure that he transformed.
On one of his nightly drinking binges, Dr. McKenna fell for a busty lounge singer and the two ended up spending the night together on the beach, Unfortunately, Dr. McKenna overslept and had to run home without even a word to his lover. He unfortunatly does not reach home in time and undergoes his second transformation.
His second transformation proves even more severe, occuring after a shorter period of exposure and lasting far longer. This fact leads radiation-poison specialist, Dr. Hoffman, to the conclusion it is likely a progressive mutation, growing more dominant the more time spends in sunlight. This is further evidenced by the fact that during his first transformation he was capable of limited speech but by the end he appears to have lost this ability. He also becomes increasingly violent both in and out of his transformed state. In the course of the film he crushed a rat in his hand, beat a dog to death with a rock, strangled a man, crashed a car into a truck, and beat several police officers to death.
Though he is never actually referred to as Sun Demon in the course of the film, he labeled Weird Killer in the front page of the fictional newspaper, Mirror News.
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