Demon Cop

When a string of unexplained murders hit Colorado Springs, the police are puzzled and without a clue as to who or what the murderer might be. A German scientist tries to warn the city about the horrifying menace. It is soon discovered that a police officer has contracted a rare blood disease that periodically transforms him into a demonic beast with an insatiable urge to kill. But does this discovery come too late? (official distributor synopsis)