Mexican serial killer, known along with her sister María de Jesús González as Las Poquianchis. From the 1950s until the mid-1960s, the sisters ran Rancho El Ángel, the locus of their large scale prostitution ring and the site of at least ninety-one murders. Guinness World Records called them the “most prolific murder partnership.”
Following a tip-off, police officers searched the sisters’ property near the city of San Francisco del Rincón, and found the bodies of eighty women, eleven men, and several fetuses. Investigations revealed that the sisters’ criminal operation recruited prostitutes through deceptive help-wanted ads for housemaids. Many of the girls were force-fed heroin or cocaine. The sisters killed the prostitutes when they became too ill, damaged by repeated sexual activity, lost their looks, or stopped pleasing the customers.
They would also kill customers who showed up with large amounts of cash. Tried in 1964, the González sisters were each sentenced to forty years in prison. Delfina died at age 58 in the jail at Irapuato on 17 October 1968 due to an accident, and Maria finished her sentence and dropped out of sight after her release. Although they are often cited as the killers, there were two other sisters who helped in their crimes, Carmen and Maria Luisa. Carmen died in jail due to cancer; Maria Luisa went mad because she feared that she would be killed by angry protesters.
The sisters and their crimes were dramatized in the Felipe Cazals film Las Poquianchis (1976) and the Jorge Ibargüengoitia novel Las Muertas (1977).

Link to Wikipedia biography