Washington DC - A top leader of Mexico's violent Jalisco New Generation cartel was sentenced to life in US prison Friday for his bloody role in creating one of the world's most powerful drug syndicates.

Ruben Oseguera Gonzalez (35) is the son of Mexico's most-wanted man – Jalisco New Generation leader Nemesio Oseguera Cervantes, who has a $15 million US bounty on his head.

Known as "El Menchito," Oseguera was convicted by a federal jury in Washington in September of multiple drug trafficking and firearms charges.

Pronouncing the life sentence, District Judge Beryl Howell said Jalisco New Generation was a "notoriously violent cartel" and that Oseguera had a "whole team of hitmen" at his command.

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Howell also ordered Oseguera to forfeit $6 billion in drug proceeds.

Anthony Colombo, Oseguera's lawyer, speaking to AFP after the sentencing, said the life term was "greater than necessary" and that he would file an appeal.

"This is a situation where no acts were committed in the US or on US territory," Colombo said. "Everything was extraterritorial. This should have been a case tried in Mexico, not in the United States."

The US-born Oseguera was second in command of Jalisco New Generation. He was captured by Mexican authorities in 2015 and extradited to the US in February 2020.

The US has offered a reward of up to $15 million for information leading to the arrest of his father, Nemesio Oseguera, known as "El Mencho."

According to court documents, the younger Oseguera directed the smuggling of "staggering" quantities of methamphetamine, cocaine, and fentanyl into the US.

Oseguera also "pioneered" the manufacturing of fentanyl in Mexico to help build his father's cartel into one of the world's most powerful drug syndicates, the Justice Department said.

He amassed a huge arsenal of weapons, according to US authorities, and killed a number of people over the years to control and expand the cartel.

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In April 2015, Oseguera "personally butchered five bound men who owed him money for drugs sold in the United States," prosecutors said in their sentencing memo.

"As described by one of the eyewitnesses, [Oseguera] slashed each of the five bound men's throats using a half-moon shaped knife, and after he was done, asked for a clean shirt."

In another notorious incident, in May 2015, cartel members acting on Oseguera's orders shot down a Mexican military helicopter hunting Jalisco New Generation leaders, killing at least nine people on board.

A Mexican federal police officer who suffered burns over 70% of his body survived the crash and was among those who testified at Oseguera's two-week trial.