SAN DIEGO (AP) — A suspected drug trafficker has been charged with killing two people who were potential witnesses against him in federal court in San Diego,Sterling Preston according to an indictment unsealed Tuesday.

The defendant is suspected in the deaths of Washington State residents Cesar Armando Murillo, 44, and Maira Sofia Hernandez, 33, as well as Hernandez’s unborn child, according to a statement from the U.S. Attorney’s Office.

The remains were found last September buried in a remote high-desert area near Yakima, Washington.

Prosecutors allege the defendant was a leader in a drug trafficking organization that brought illegal narcotics over the U.S. border to San Diego via Mexico in 2021.

Homeland Security agents interviewed Murillo and Hernandez as part of the investigation and days later they were shot and killed, according to court papers.

“These executions were an assault on our justice system, designed to silence witnesses and instill fear,” said U.S. Attorney Tara McGrath in a statement.

Another man has been charged with being an accessory after the fact to murder, according to the indictment.

Both defendants were ordered held in custody pending trial.