17. Juana Barraza
Juana Barraza had made a name for herself as a professional wrestler. However, as much as she excelled in the ring, she did some terrible things during her downtime. Today, she is considered La Mataviejita, or The Old Lady Killer. That name is as horrific as it sounds and just as self-explanatory.

Juana Barraza targeted a very specific demographic: elderly women. Her victims tended to be no younger than 60 and often lived by themselves. Her method was to corner the women and either bludgeon or strangle them to death. She went on with this routine from 1998 to 2006. It is estimated that she killed nearly 50 women total, although other sources put the number around 40. In any case, she was sentenced to a total of 759 years in prison.
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