Alleged drug trafficker pleads guilty to killing witnesses, including pregnant woman

A man charged in the killings of a man and his pregnant wife to keep them from testifying in a San Diego drug trafficking case pleaded guilty to federal charges Monday.

Benjamin Madrigal-Birrueta is slated to be sentenced next year in connection with the slayings of Cesar Armando Murillo, 44, and Maira Sofia Hernandez, 33.

Prosecutors said the victims each died of multiple gunshots to the head and their bodies were buried in a desert area near Yakima, Washington.

According to the U.S. Attorney’s Office, Madrigal-Birrueta had a leading role in a drug trafficking enterprise that involved using stolen vehicles to smuggle drugs through San Diego-area ports of entry.

The investigation into the drug smuggling led agents to Yakima, where investigators interviewed Murillo and Hernandez in August of 2022.

Federal prosecutors said both were murdered “within days of those interviews.” Following search efforts that exceeded a year, the victims’ bodies were recovered in the fall of 2023.

Madrigal-Birrueta’s plea agreement states that he and other co-conspirators fatally shot Murillo on Aug. 28, 2022, at a ranch just outside Yakima. The plea agreement states Madrigal-Birrueta maintains that Murillo also fired gunshots at him and his co-conspirators, though no one was struck by that gunfire.

Less than a week later, Madrigal-Birrueta persuaded a “visibly pregnant” Hernandez to come to the ranch because he said Murillo “was waiting for her at the ranch and wanted to see her,” the plea agreement states.

Madrigal-Birrueta then drove Hernandez to the ranch, where his co-conspirators shot and killed her, the document states. The U.S. Attorney’s Office said both victims’ bodies were buried near the ranch at Madrigal-Birrueta’s direction.

Along with admissions to his involvement in Murillo and Hernandez’s killings, the plea agreement states he caused the death of the couple’s unborn child. The U.S. Attorney’s Office said Hernandez was six months pregnant at the time of her death.

Updated at 5:19 p.m. Monday, Sept. 22, 2025