The first two bodies were found in Lovers' Lane. The man was dead. His girlfriend, still alive, described the stick-up artist as of medium build, wearing glasses, mild-mannered, and courteous. If was a description that fit half the male population of Los Angeles. It was almost the only clue Joe Friday and Frank Smith had to catch the murderer. <P>Then the courteous killer struck again – and again! The last time Joe Friday was waiting for him with a gun. When the criminal escaped with only a bullet wound, he vowed revenge – and mailed an unsigned, misspelled note that read: YOU THINK YOUR A SMART BADGE. NOBODY BURNS ME AND LIVES, COP. START SWEATING.