Since the 1990s, Colombian trafficking groups have ceded much of their international networks to Mexican organizations, taking on a smaller role in the business. However, drug gang the Rastrojos are bucking the trend and retaining some of their European networks.

Spain's Supreme Court recently handed down sentences ranging between 20 and 35 years to members of a Colombian gang known as the "Señores de Acido" (the Lords of Acid) for crimes including kidnapping, homicide, and arms trafficking. The group, which was run from Colombia by Luis Eduardo Davalos Jimenez, alias "Pampo," were arrested in 2008, and had been acting as an "oficina de cobro" for the Rastrojos in Spain, controlling debt collection, trafficking, extortion rackets, and carrying out assassinations. Davalos was detained in the Colombian city of Cali, a Rastrojos stronghold, in November 2009.

The oficina gained notoriety for the murder of one of Davalos' relatives in Madrid in September 2007. After kidnapping their victim, the group removed one of his hands, the fingers of his other hand, and then beheaded him before dissolving his body in acid, reported El Espectador. The motive behind the murder, along with numerous others ordered by Davalos, was to resolve drug-related debts.

Though the brutal nature of their assassinations may be unique, the presence of a cell of a Colombian gang in Spain is not. In May last year, Heider Augusto Sarria Martinez, alias "Niño Malo," ("Bad Boy") was arrested in Cali, accused of having run another oficina for the Rastrojos in a role not dissimilar to Davalos. At the time of his arrest, intelligence officials stated he had settled in Spain between 2003 and 2007 in order to secure drug trafficking routes for the Colombians. He then returned to Cali, being entrusted by the Rastrojos leaders, brothers Javier Antonio and Luis Enrique Calle Serna, to run the gang's Spanish oficina along with others throughout Colombia, reported El Tiempo.

Also last year, a 520 kilo shipment of cocaine, allegedly belonging to the Rastrojos and bound for Valencia, was interdicted by Colombian authorities in the Pacific port city of Buenaventura. The cargo would have had a retail price of just over $20 million.

A further two arrests took place this month. On March 8, Spanish police arrested alias "Celemin," accusing him of trying to set up an oficina for the Rastrojos out of Madrid. In a higher-profile case, Rafael Ivan Zapata Cuadros, alias "Rasgao," was detained in the Colombian department of Antioquia on March 18. He is said to have been a crucial link between the Rastrojos and other European drug traffickers -- principally the Italian mafia -- helping them to create and secure trafficking routes throughout Spain, France, Holland, Germany and Austria. He had had an Interpol "red notice" (international arrest warrant) against his name and has since been sentenced to 20 years in Italy for drug trafficking, reports El Espectador.

The extent to which Colombian drug gangs run their own networks abroad has been on the decline for the last two decades, making the Rastrojos' actions in Europe particularly unusual. As Jay Bergman, Andean regional director for the US Drug Enforcement Administration (DEA), told InSight Crime, Colombian gangs have assumed the role of global wholesaler, with their trafficking routes typically being taken over by Mexican cartels.

The reasons for this are many. The monolithic Medellin and Cali Cartels of the 1970s, 1980s and, to a lesser extent, 1990s, have long fallen, replaced by a fragmented collection of trafficking groups. This is the result of blows dealt to Colombia's criminal infrastructure by a sustained crackdown from both domestic and US forces in recent decades.

The fall of Colombia's major cartels created a vacuum which the Mexicans moved to fill. According to some, this transition, as well as being forced by external pressures, was a conscious move on the part of both sets of cartels, with the Colombians agreeing to cede control of their trafficking routes to the Mexicans in the 1990s in exchange for a "behind the scenes" role. By taking themselves out of the spotlight, the Colombian gangs could shield themselves from capture while still retaining profits at wholesale price (around one quarter of retail price according to the UN's 2011 World Drug Report) thanks to the country's status as the world's major cocaine producer.

Given the transformation of the global drug trafficking landscape, it seems pertinent to ask why the Rastrojos are seemingly making efforts to retain their footing in Europe. The best answer may be the most simple one; the financial gain is simply too good to give up.

The executive director of the UN Office on Drugs and Crime (UNODC), Yury Fedotov, said last year that Europe's cocaine market, with an estimated worth of $33 billion, had almost reached the level of the $37 billion US market. Furthermore, it is continuing to grow, unlike in the US where cocaine consumption has largely stagnated, if not declined, over the last decade.

The US market may still be bigger, but the Rastrojos, or any other Colombian gang, has little chance of wresting control from its larger Mexican counterparts, thanks to their proximity. To try would not only be futile but counterproductive, risking their crucial business ties with Mexican cartels.

In contrast, the incursion by Mexican cartels into Europe is a comparatively new development, and many of the trafficking routes to the continent are far closer to Colombia than Mexico, with key corridors running through Venezuela. Unlike trafficking routes to the US, these remain in the hands of Colombian groups more than of Mexican groups.

Of course, the role of the Rastrojos in Spain, while unusual, must not be overstated. Mexican cartels are expanding their influence in Europe and the global trafficking dynamic has shifted greatly in their favor. However, the examples of Rastrojos-affiliated bands operating in the Old World show that, where business dictates, Colombian drug gangs may find it worthwhile to buck the trend.