On March 6, 1981, Marianne Bachmeier walked into a courtroom in Lübeck, Germany—and within moments, shocked the world. She pulled a pistol from her purse and shot Klaus Grabowski, the man accused of kidnapping and murdering her 7-year-old daughter, Anna. He died on the spot. Marianne showed no remorse and was immediately arrested. Anna had been taken in May 1980...