(CNN) Federal prosecutors want drug kingpin Joaquin "El Chapo" Guzman to forfeit more than $12.6 billion to the United States government, a court filing shows.

The proposal, filed by prosecutors Friday, indicates the massive sum represents property "constituting or derived from" his narcotics-related crimes and the property that "facilitated the commission of those crimes."

"It's insane to think that Guzman would have all that money," said Mariel Colon, one of Guzman's attorneys.

Guzman, once the leader of the murderous Sinaloa drug cartel in Mexico, was convicted in February of running a continuing criminal enterprise and several other drug-related charges.

Several witnesses, including some of Guzman's associates, testified during his months-long trial that they would sell a kilogram of cocaine in New York for up to $35,000 and the same amount of heroin elsewhere for an average of $55,000, the filing states.

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