The founder of the feared Los Zetas drugs cartel has been deported to Mexico after serving a lengthy jail sentence in the United States.

Osiel Cárdenas Guillén, 57, led Los Zetas until 2003, when he was cornered by Mexican soldiers near his hometown of Matamoros.

Under his leadership, the group became one of the most powerful and brutal hit squads in the Mexican drug wars.

US immigration officials handed Cárdenas over to Mexican police at the Otay border crossing, where he was quickly re-arrested and taken to El Altiplano maximum security jail in Mexico state.

Mexican prosecutors said he had been arrested on charges of murder and organised crime dating back to his time as one of the most powerful drug lords in Mexico.

Cárdenas Guillén made his criminal career in the Gulf drugs cartel in the 1990s, reportedly not shying away from having his allies killed to rise to the top, a practice which earned him the nickname of "Mata Amigos" (Spanish for "killer of friends").

But what he became infamous for was recruiting members of Mexico's elite special forces and using them as hitmen and enforcers for the Gulf cartel.

The law enforcers-turned-contract killers became known as Los Zetas.

The brutal methods they used, such as decapitating and dismembering their victims, quickly spread terror through the north-eastern part of Mexico which was their stronghold.

By the early 2000s, Cárdenas Guillén was one of the most wanted men in Mexico.

Mexican security forces managed to apprehend him in his home state of Tamaulipas in 2003 after a bloody gun battle.

Aware of the power the gang leader wielded in the area, the security forces quickly flew him to the capital, Mexico City, were he was put into pre-trial detention.

In 2007, he was extradited to the US.

There, he was charged not just with trafficking tonnes of cocaine into the US but also with threatening to assault and murder federal agents.

He pleaded guilty in 2010 and was sentenced to 25 years in jail.

Having served a large part of his sentence, he was released in August of 2024 from federal prison in Terre Haute, Idaho, and handed over to US Immigration and Customs Enforcement.

This paved the way for his deportation to Mexico on Monday.

Mexican prosecutors said there were seven federal cases still open against Cárdenas Guillén and that he could be sentenced to a total of more than 700 years in prison if found guilty on all charges.