A man who claimed to be a ‘serial killer’ once called up The Howard Stern Show to openly admit that he killed 12 prostitutes. The disturbing phone call was recorded during a 1997 episode of the American radio show, and has since resurfaced on social media. Going by the name ‘Clay’, he rang up saying he planned on leaving clues for the detectives at the various crime scenes, but it wasn’t needed. “I wanted to baffle people, but it turned out that no one noticed for a long time,” he told host Howard Stern. “I never sent the clues, I…