Delfina and Maria de Jesus Gonzales - 91 murders
Where: Guanajuato, Mexico
When: 1960s
Sisters Delfina and Maria de Jesus Gonzales, owners of a Mexican brothel, killed the prostitutes they recruited and an unknown number of clients. They were arrested in 1964 after police found the bodies of 91 people during a raid on the bordello. They were sentenced to 40 years in prison.