Drug trafficker killed and buried 2 witnesses to silence them, feds allege. One was 6 months pregnant

Dozens of firearms are spread out on a table.
A murder investigation of an alleged drug trafficker turned up dozens of weapons.
(U.S. Attorney’s Office, Southern District of California)

A man accused of running a drug trafficking operation was charged by federal prosecutors Tuesday in the killing of two witnesses, allegedly to keep them from testifying against him.

Special agents with Homeland Security Investigations were following a lead when they traveled to Yakima, Wash., in August 2022 to interview Cesar Armando Murillo, 44, and Maira Sofia Hernandez, 33, who was six months pregnant, according to court filings.

Days after they were interviewed, federal prosecutors said, the two were murdered and buried in the desert.


Both appeared to have been killed with multiple gunshot wounds to the head, according to the U.S. attorney’s office.

The man behind the killings was 22-year-old Benjamin Madrigal-Birrueta, prosecutors said in a federal indictment that was unsealed Tuesday. Federal investigators allege Madrigal-Birrueta was the leader of a criminal enterprise that used stolen late-model cars to smuggle drugs across the U.S.-Mexico border in the San Diego area.

According to the indictment, Murillo and Hernandez had allegedly wired money to people connected with the drug trafficking ring, and registered vehicles that were used in the operation.

Their bodies were not found for more than a year, until Sept. 13, 2023, officials said. The intensive search involved geophysicists, ground-penetrating radar, laser imaging, chemical testing of soil, and cadaver dogs.

The man accused of killing three women in a crash in Pomona over the weekend has been charged with murder in connection with the collision, authorities announced Tuesday.

March 5, 2024

“The murder of witnesses is an affront to our rule of law but HSI, along with our law enforcement partners, have the resources to uncover these horrible crimes,” Special Agent in Charge Robert Hammer, who oversees Homeland Security Investigations in the Pacific Northwest, said in a statement.

Federal investigators began looking into the operation around August 2021, after several vehicles were spotted and seized in San Diego-area ports of entry, according to the U.S. attorney’s office.


Officials seized methamphetamine, cocaine and fentanyl during their investigation, officials said.

The search also resulted in the seizure of multiple firearms, including a machine gun and body armor.

Madrigal-Birrueta is believed to have run the operation from Yakima, officials said.

There was no description of who shot the arrow at the victim or what led to the incident.

March 5, 2024

He is facing multiple charges in federal court, including two counts of murder, conspiracy to import controlled substances, conspiracy to commit witness tampering, causing death of a child in utero, and multiple charges of possessing firearms in furtherance of a drug trafficking crime.

The Times was unable to reach out to an attorney for the accused; no legal representative is yet listed.