Irapuato, Guanajuato
María Delfina González Valenzuela (1912, El Salto, Jalisco, Mexico - 17 October 1968, Irapuato, Guanajuato, México), María del Carmen González Valenzuela (1918 - 1949), María Luisa González Valenzuela (1920 - 19 November 1984, Irapuato, Guanajuato, México) and María de Jesús González Valenzuela (1924 - 1990), known as "Las Poquianchis," were four sisters from the north-central Mexican state of Guanajuato. From 1945 until 1964, the sisters ran "Rancho El Ángel"', the locus of their largescale prostitution ring and the site of the murder of at least 91 people, but it is believed that the four sisters killed more than 150 people or even more than 200 people. Guinness World Records called them the "most prolific murder partnership".