SAN DIEGO (Border Report) — The remains of a man believed to be in his early 20s were found in a shallow grave on Thursday in Mexico just south of the Arizona-California state line.

The body was located in an area where 11 others have been dug up by volunteers in recent weeks.

There are several groups of citizens in Baja California dedicated to finding the remains of people who have disappeared or have been kidnapped.

They often respond to anonymous tips about where people might be buried or where mass graves can be found.

Upon discovering remains, volunteers call police and the state’s medical examiner’s office.

At another site dubbed the “Narco Cemetery,” discovered in the same general area last month, volunteers have recovered 19 bodies so far.

Both locations are believed to be sites where a band of assassins who call themselves “The Russians” bury the people they kill.

The group reportedly has ties to the Sinaloa Cartel once operated by Joaquin “El Chapo” Guzman.

Ismael “El Mayo” Zambada is said to be the head of the Sinaloa Cartel. (Courtesy: DEA)

His sons, known as the “Chapitos,” are in a power struggle for control of the organization with Ismael “El Mayo” Zambada, who is now running the cartel, according the U.S. Drug Enforcement Administration.

The U.S. Drug Enforcement Administration is offering $15 million for information leading to Zambada’s arrest.