Mexico formally began extradition proceedings of recaptured drug lord Joaquin "El Chapo" Guzman to the United States, the Attorney General's Office said Sunday. Guzman was arrested Friday, six months after he escaped through a tunnel out of Mexico's maximum-security Altiplano prison.

Guzman was notified by agents of the international police agency Interpol Sunday that two arrest warrants from the U.S. were being processed against him. The U.S. government reportedly wants Guzman to be tried on trafficking charges. Mexican officials, however, cautioned that the extradition process could take several months.

The 57-year-old’s attorney Juan Pablo Badillo said the defense has already filed six motions to challenge extradition requests, the Associated Press (AP) reported. Badillo reportedly said that Guzman should not be extradited to the U.S. because "our country must respect national sovereignty, the sovereignty of its institutions to impart justice."

A Mexican federal law enforcement official, who spoke on condition of anonymity, told the AP that the earliest Guzman could be extradited would be six months, but even that may extend because lawyers will file appeals.

Guzman was recaptured Friday in northwest Mexico in his home state of Sinaloa, after a gun battle with authorities. Five suspects were killed and six others were arrested.

Mexican authorities reportedly said that actor Sean Penn's contacts with Guzman helped them track the fugitive.

According to reports, Mexican actress Kate del Castillo orchestrated Penn’s secret interview with Guzman. Penn said Saturday in a story he wrote for Rolling Stone magazine that Castillo played an important role in brokering the in-person meeting with Guzman and also served as a translator.