Leonel Torres Herrera was born on September 7, 1947, in McAllen, Texas, as the second of five children in a poor Mexican-American family. His upbringing was marked by poverty and domestic abuse; his father, José, was an alcoholic who frequently beat his wife and children. Leonel's mother, Maria, married José at the age of 14 and endured years of violence. As a child, Leonel suffered from chronic illnesses and multiple head injuries, and he often tried to protect his mother from his father's abuse. He excelled in sports but dropped out of high school during his senior year. Leonel joined the U.S. Navy and served in Vietnam, where he experienced combat. Upon returning, he exhibited signs of paranoia and mental instability, including trance-like states and delusional behavior. He later became involved in drug trafficking with his father and brother, Raul, and developed a cocaine addiction.

On September 29, 1981, Texas Department of Public Safety Officer David Rucker was found shot to death beside his patrol car on a highway near Los Fresnos, Texas. Shortly thereafter, Los Fresnos Police Officer Enrique Carrisalez stopped a speeding vehicle matching the description of a car seen leaving the scene. As Carrisalez approached, the driver shot him in the chest; Carrisalez died eight days later. Evidence collected included Herrera's Social Security card near Rucker's body, blood matching Rucker's type on Herrera's clothing, and a handwritten letter implying guilt found on Herrera. Carrisalez, before dying, identified Herrera from a photograph as his assailant. Herrera was arrested on October 4, 1981, and charged with both murders. In January 1982, he was convicted of Carrisalez's murder and sentenced to death; he later pleaded guilty to Rucker's murder.

Years later, new evidence emerged suggesting Herrera's brother, Raul, had confessed to the murders. Affidavits from Raul's former attorney, a cellmate, and Raul's son, who claimed to have witnessed the crimes, supported this claim. Despite this, the courts denied Herrera's appeals, stating that claims of actual innocence based on new evidence did not warrant federal habeas relief without a constitutional violation. The U.S. Supreme Court upheld this decision in Herrera v. Collins, ruling 6–3 against Herrera. He was executed by lethal injection on May 12, 1993, maintaining his innocence until the end.