In the final hours of 2015, Colombian President Juan Manuel Santos tweeted to announce the capture in Peruof Carlos Arturo Hernández Ossa, alias "Duncan," bestowing on the fugitive drug lord the title of the last great capo of a criminal organization whose roots can be traced back to Pablo Escobar and the Medellin Cartel.

Duncan's criminal career began when he passed from the ranks of the Colombian army into the paramilitary network of the United Self-Defense Forces of Colombia (AUC) after he was caught selling military arms to the guerrillas of the National Liberation Army (ELN). His military expertise was put to use by the AUC and in the early 2000s InSight Crime encountered Duncan training paramilitary recruits at a camp in the north of the department of the department of Antioquia.

Duncan was deployed to the Antioquian capital of Medellin to combat the guerrilla militias that had seized control of many of the city's periphery slums. There he worked with Diego Murillo, alias "Don Berna," who had emerged as the criminal overlord of Medellin after the fall of Pablo Escobar while simultaneously garnering enormous power as a paramilitary chief within the ranks of the AUC.

The AUC demobilized between 2003 and 2006 after striking a deal with the Colombian government and Duncan was among those to hand in his weapons. However, rather than rejoin civilian life, he assumed control of a rural faction of the Oficina known as thePaisas, as well as maintaining influence in Medellin itself.

In 2008, Don Berna was extradited to the United States sparking turmoil in the Oficina. With the leadership collapsing around him, Duncan became one of, if not the most powerful Oficina chief at large. However, just months after Berna's extradition, Duncan was arrested.

Although Duncan was only sentenced to three years in prison on charges of using false documents, he escaped in 2010 after first securing permission to see out his sentence under house arrest.

Until his recapture, Duncan continued to run drug trafficking routes and organized crime networks in Medellin, often from abroad, until police finally caught up with him in Peru, reportedly by tracking his lover as she visited from Colombia.

InSight Crime Analysis

The depiction of Duncan as the "last great capo" of the Oficina de Envigado is misleading for several reasons. Firstly, far from being the head of the Oficina, he was in fact one of several leading figures within the organization and there is no indication he was the most powerful or significant.

In addition, the Oficina itself is no longer a coherent monolithic organization, but a federation of criminal businesses that together perform an important if limited role in the Colombian underworld, whereas titles such as "capo" are throwbacks to the now defunct era of cartels and kingpins.

The restructuring and evolution of the Oficina de Envigado began when the extradition ofDon Berna and the arrests and deaths of his key lieutenants unleashed a fratricidal war of succession between two key figures, Erickson Vargas Cardenas, alias "Sebastian," and Maximiliano Bonilla Orozco, alias "Valenciano."

Critically this war not only divided factions of the Oficina but also business interests; while Sebastian had greater influence with the city's gangs and their Medellin based criminal activities, Valenciano had more control over the group's international drug trafficking networks. Sebastian eventually emerged victorious but he was left to rule over an organization that had lost much of its influence in transnational drug trafficking.

Sebastian had little time to piece back together the organization and was arrested in August 2012, leaving no clear successor. Sensing weakness, a new enemy soon appeared, the Urabeños, a narco-paramilitary group that emerged from the demobilization of theAUC. The Urabeños moved to seize control of Medellin through a combination of military might and strategic alliances in a new war for the city.

This war was brought to an end not through military victory, but through a negotiated pact between the two sides in which they agreed to halt the fighting and cooperate on drug trafficking. Underworld sources told InSight Crime this agreement was brokered by powerful players with interests in both the underworld and legal world who believed the violence was damaging their interests. Several sources have also indicated that Mexico's Sinaloa Cartel may have played a part in these negotiations as it sought to re-establish its reliable cocaine supply, which had been put at risk by the fighting and instability in the Colombian underworld.

The wars and divisions have left the Oficina a very different structure to the one run byDon Berna and with a different role in the underworld. The Oficina has always consisted of semi-autonomous factions at each level, from the estimated 120-350 street gangs that operate at a neighborhood level to the large structures the police refer to as ODIN (Criminal Organizations Integrated with Drug Trafficking). However, now these factions are no longer united under one command, but instead operate as a coalition whose ties to each other often stretch no further than mutually beneficial business and fear of stepping out of line.

According to the police, there are 14 ODIN in Medellin but three of these have been severely debilitated. It is not clear how many of these networks have a seat at the top table of the Oficina leadership, but what is clear is that recent years have seen a clear restructuring in the Oficina hierarchy, with once powerful figures murdered or arrestedwhile others emerged from the mid-levels of the underworld to claim greater power and status.

The most spectacular rise has been that of alias "Tom," and his organization Los Chatas. Previously, Tom had been a mid-level gangster while Los Chatas had been largely confined to a Medellin satellite town, Bello, where they competed with more established structures over local criminal activities such as extortion.

However, by the end of 2015, Los Chatas had made it onto the US Treasury's "Kingpin List" of international organized crime networks and, at least according to the Colombian security forces, were running large cocaine crystallization laboratories in partnership with the Urabeños in rural Antioquia. Tom meanwhile has been described as the new military head of the Oficina.

The key to the rise of Tom and Los Chatas may lie in reports they struck their own pact with the Urabeños. According to the US Treasury, Tom is now the main liaison between the Oficina leadership and the Urabeños and has been charged with maintaining the agreement between the two sides -- a position of significant power in the new look underworld. In addition, according to intelligence sources speaking to El Colombiano, the alliance with the Urabeños has also allowed Los Chatas to project their power beyond the confines of metropolitan Medellin and into drug trafficking territories in the department of Antioquia.

The current role of the Oficina in the Colombian underworld is varied. In Medellin and its surrounds, the various factions of the Oficina have vast criminal portfolios and make millions running or taking a cut from extortion, drug sales, robberies, sex trafficking,contraband and even obscure activities such as trading basic food products or renting out properties. While the profits to be made from such low level crimes are dwarfed by drug trafficking, they are still lucrative -- according to a recent study by the University of Antioquia and EAFIT University, the Medellin extortion and robberies trade alone is worth an estimated $18 million a year.

The Oficina factions also provide key services to an array of actors in the drug trade, specializing in debt collection, money laundering and assassinations. According to the US Treasury, transnational partners such as the Urabeños and Mexico's Sinaloa Cartel have come to depend on the Oficina for such services.

However, what is less clear is the extent of the Oficina's own transnational drug trafficking. In its designation of the Oficina, the US Treasury says the network is directly involved in international drug trafficking as well as "secondary activities" such asextortion, money laundering activities and contract killing, yet the truth may well be the reverse.

It is likely senior figures with years of experience in the underworld such as Duncan maintain drug trafficking contacts and routes, and that up and coming players such as Tom may be seeking their own claim on the upper reaches of organized crime. However, as an organization, it is more likely the "secondary" activities are now the Oficina's main purpose and their primary function is as muscle and money launderers for the powerful drug traffickers that remain hidden in the shadows of the modern Colombian underworld and transnational networks such as the Urabeños and the Sinaloa Cartel.