U.S. federal prosecutors says the death penalty is not off the table for renowned Mexican cartel boss Rafael Caro Quintero.

Although they have yet to formally to formally seek capital punishment, prosecutors for the Eastern District of New York attending Caro Quintero’s arraignment last week in Brooklyn were noncommittal on the subject.

Caro Quintero, 72, is accused of the murder of DEA agent Enrique “Kiki” Camarena in Guadalajara in 1985, and channeling tons of heroin, methamphetamine, marijuana and cocaine into the U.S. over decades. He served almost 30 years in jail in Mexico for his crimes, before being expelled to the United States, along with 28 other imprisoned drug traffickers, on February 27.

None of these individuals were officially extradited but rather “expelled” from Mexico under a provision of the national security law which allows the Mexican government to bypass the formal extradition process.

The rapid move to deport its own citizens with no due process came as Donald Trump threatened to impose harsh trade tariffs on Mexico for failing to stop the flow of migrants and drugs across the border.

Traditionally, Mexico has a strong stance against the death penalty and does not extradite individuals to countries where they could be sentenced to death. Mexico has fought bitterly for decades to stop the U.S. government from executing its citizens. The extradition treaty, a form of which has been in place since the 1970s, stipulates that whichever country requests a defendant cannot impose the death penalty if it is not present in the defendant’s home country.

However, the Mexican government appears to be prepared to comprise its core principles in light of the considerable pressure the U.S. government is now exerting on Mexico.