Former right-wing paramilitary commander Hernan Giraldo, wanted in Colombia for numerous massacres, disappearances and rapes, was arrested at Bogota airport Monday after being deported from the United States where he had served 12 years in prison for drug trafficking, officials said.

"Hernan Giraldo Serna, known also as 'the Lord of the Sierra,' has just landed in Colombia," Colombia's immigration bureau told reporters.

Also known as "The Boss," the much-feared paramilitary leader, now aged 72, was one of the leaders of the far-right militias who waged a ruthless struggle against left-wing guerillas in Colombia until their demobilization in 2006.

Giraldo is wanted under more than 40 warrants for crimes committed under his command by the Tayrona Bloc of the Self-Defense Units of Colombia, which operated in the north of the country, the bureau said.

He oversaw a reign of terror in the mountainous region of Magdalena, where the Sierra Nevada de Santa Marta rises to some 5,000 meters (16,404 feet) along the Caribbean coast, and where narco-plantations flourished.

In 2008, he was extradited to the United States, where he was jailed for 12 years on charges of conspiring to produce and distributing cocaine.

Colombian immigration agents escort former paramilitary leader Hernan Giraldo upon his arrival and arrest in Bogota on January 25, 2021
Colombian immigration agents escort former paramilitary leader Hernan Giraldo upon his arrival and arrest in Bogota on January 25, 2021 Colombian Migration Office / -

Norma Salazar, a researcher for the Women of Magdalena Network, talked to 200 of his victims, "all aged under 14," who were sexually abused.

"Nowhere in the modern world has there been such a predator," the human rights activist told AFP, adding that his return to Colombia has triggered "fear, anxiety and terror" among his victims.

He led the Tayrona Bloc militia together with Rodrigo Tovar, who was recently extradited to the United States, and who was a key figure in the "para-politics scandal" that saw dozens of lawmakers jailed for having forged alliances with far-right militias.

The two leaders were demobilized at the same time as some 30,000 other paramilitaries during the time that Alvaro Uribe led the country from 2002-10.

The self-defense militias were put under a special branch of the justice system that set out a maximum sentence of eight years in jail if they laid down their arms and confessed to their crimes.

Giraldo was appearing before judges to give his version of his crimes when Uribe's administration extradited him to the United States after accusing him of returning to crime from prison.

That decision to extradite was contested by human rights groups, who argued that it denied victims the chance to discover the full truth and to be properly compensated.