BOGOTA -- One of Colombia's most-feared right-wing warlords has been released from jail and apologized Friday for his atrocities.

Freddy Rendon, better known by his alias "El Aleman," "The German," walked free from a maximum security prison in Medellin late Thursday.

Speaking to Blu Radio less than 24 hours later, the former paramilitary commander said he was "regretful and embarrassed" over heinous crimes committed by his 1,500 troops in the northern Gulf of Uraba region during the bloodiest chapter of Colombia's long-running conflict in the 1990s.

Among the atrocities he was pressed about on air was the 1997 decapitation of a peasant farmer, Marino Lopez, whose murder during a joint army-paramilitary operation led the Inter-American Court of Human Right to condemn the Colombian state in 2013.

In the interview, Rendon acknowledged that one of his combatants, without authorization, did slash off Lopez's head with a machete. But he denied witness testimonies that the severed head was then used as a soccer ball to instil fear in the community.

"This is borderline morbid and a sort of psychological depravity," he said.

Rendon is the most senior paramilitary commander to be freed after completing the maximum eight years stipulated in a law for former militia members who confess their war crimes to prosecutors and compensate victims. More than 30,000 militia members laid down their arms between 2003 and 2006 as a result of a peace deal with former President Alvaro Uribe.

Several other paramilitary leaders are in line to be released, but their furloughs are held up over objections they aren't fully co-operating with the justice system.

The 13 most important commanders of the United Self-Defence Forces, or AUC, were extradited in 2008 to the United States, where they are expected to serve much longer sentences on drug-trafficking charges.

Rendon escaped a similar fate because the U.S. didn't formally make a request for him until well after the mass extradition. Then in 2010 Colombia's constitutional Court rejected the request, saying he first had to answer for his crimes in Colombia.

Now freed, Rendon said he hopes to remain in Colombia and contribute to peace at a time the government is negotiating with the AUC's former battlefield enemies, the Revolutionary Armed Forces of Colombia.

"We have to stop this war," he said.