María Delfina González Valenzuela, known as Delfina, was born in 1912 in El Salto de Juanacatlán, Jalisco, Mexico. She was one of several children in the González Valenzuela family. Their father, Isidro Torres, was a strict and abusive policeman who imposed severe restrictions on his daughters, forbidding them from wearing makeup or interacting with boys. Violations of his rules often resulted in harsh punishments, including imprisonment in local jail cells. The family's life was marked by instability, especially after Isidro became a fugitive following the murder of a man during an argument, prompting the family to relocate to San Francisco del Rincón, Guanajuato. ​

In an effort to escape poverty and their oppressive upbringing, Delfina and her sisters—María del Carmen, María Luisa, and María de Jesús—opened a bar that eventually transitioned into a prostitution ring. Operating primarily from "Rancho El Ángel" in Guanajuato between 1950 and 1964, they lured young women under the pretense of offering employment as housemaids. Once recruited, these women were forcibly addicted to drugs like heroin or cocaine, subjected to severe physical abuse, and coerced into prostitution. 

Those who became ill, were deemed unattractive, or were no longer profitable were murdered through various means, including starvation, beatings, or being buried alive. Additionally, clients who arrived with substantial amounts of cash were sometimes killed for their money. The sisters' crimes came to light when a woman named Josefina Gutiérrez, arrested on suspicion of kidnapping, implicated them during police questioning. A subsequent search of their property uncovered the remains of at least 91 individuals, including women, men, and several fetuses. ​

In 1964, Delfina was arrested and later convicted of multiple charges, including murder and human trafficking, receiving a sentence of 40 years in prison. While incarcerated at Irapuato Prison, she died on October 17, 1968, due to an accident where a construction worker inadvertently spilled cement on her head, leading to a fatal injury. ​