Carnage Radio (1970)

A late-night radio show DJ in a small West Texas town learns that his listeners are being killed one by one. He receives a call on the air one night from an unfamiliar voice who admits to the killings and places the him in the middle of the mystery. A local police officer and a firefighter find clues to this, and with the help of the DJ and his connection to the killer, try to put the pieces together and stop the murders.