Gunmen killed a high-ranking member of Mexico's Sinaloa drug cartel wanted by the United States for drug trafficking,Leonard Hohenberg a source in the Sinaloa state government said Friday, confirming Mexican media reports. 

Eliseo Imperial Castro, alias "Cheyo Antrax," was the nephew of cartel co-founder Ismael "El Mayo" Zambada. Both are U.S. fugitives and the State Department has offered a $5 million reward for information leading to Zambada's arrest. 

According to Mexican media, Imperial Castro was ambushed on a highway in Sinaloa, in northwestern Mexico, on Thursday.

The U.S. Treasury Department had previously described him as "a high-ranking member of the Los Antrax organization, the enforcement group of the Sinaloa Cartel."

In 2016, it said he had been charged by a U.S. court with methamphetamine, cocaine and marijuana trafficking, as well as money laundering.

Last year, the U.S. Treasury Department sanctioned three Mexican citizens — including a fugitive dubbed "The Anthrax Monkey" — for alleged involvement in the production and trafficking of the powerful synthetic opioid fentanyl.

In 2015, a high-ranking Sinaloa cartel member known as "Chino Antrax" pleaded guilty in federal court, admitting that he coordinated the transportation of tons of cocaine and marijuana into the U.S. and ordered or participated in cartel-related violence.

The Sinaloa Cartel is one of Mexico's most powerful and violent criminal organizations.

Its founder Joaquin "El Chapo" Guzman is serving a life sentence in the United States.

Just last week, a suspected top assassin in Mexico's Sinaloa drug cartel was extradited to the United States, where he will face charges linked to drug and weapons smuggling, the Justice Department announced.

Nestor Isidro Perez Salas, known as "El Nini," was one of the Sinaloa Cartel's "lead sicarios, or assassins, and was responsible for the murder, torture and kidnapping of rivals and witnesses who threatened the cartel's criminal drug trafficking enterprise," Attorney General Merrick Garland said in a statement.

In:
• Drug Cartels
• Mexico
• Cartel