Now investigators are trying to solve the twisted tale of a woman who was known as Lady Bluebeard. How many people did she kill? And did she fake her own death? Her husbands and children seemed to have a habit of turning up dead, another difference between male and female serial killers. Male serial killers usually don’t know their victims.
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[Full disclosure: I've written probably 10 or 11 mysteries and thrillers, but never with a serial killer, because I just don't want to spend 6-10 months in that person's head.]