After becoming a key witness for the DEA, one of the former members of the Cali Cartel is reportedly back in his old territory and waging a bitter war against one of the most powerful drug gangs in Colombia, with up to 500 dead already.

Colombian newspaper El Espectador reported that Victor Patiño Fomeque, a former associate of the Cali Cartel, is engaging in a war against the heirs of Cali and the Norte del Valle Cartels, the Rastrojos.

Patiño was extradited to the U.S. in 2002 and served a reduced sentence after becoming a witness for the Drug Enforcement Administration (DEA). While Patiño named names, his former associates back in Colombia began methodically killing off members of his family. According to some accounts at least 35 members of the Patiño Fomeque clan were killed.

Patiño returned to Colombia in 2010 and began plotting revenge. The new generation of gunmen, now grouped under the Rastrojos, have replaced the Cali and Norte Del Valle Cartels, controlling drug trafficking along the Pacific Coast. To strike back against the Rastrojos, including their leader Javier Antonio Calle Serna, alias “Comba,” and his brother Luis Enrique Calle Serna, Patiño struck a deal with a rival group, the Caribbean-based Urabeños, who provided him with men and arms. Already battling the Rastrojos in northern departments like Antioquia and Santander, the Urabeños were interested in confronting the Calle Serna brothers on their home turf.

So far this year the resulting gang war is behind at least 500 murders in southwest states like Valle del Cauca and Nariño, police told El Espectador. Patiño, believed to run most of his operations from Ecuador, is now thought to control an armed group of up to 1,000 combatants.

Patiño is also reportedly receiving aid from another former Norte del Valle Cartel associate. This partner, Martin Fernando Baron, alias “Martin Bala,” has his own reasons to try and lash back at the Calle Sernas: they reportedly tried to have him killed in 2005.

Baron played a leading role in the Cali mafia wars between 2003 and 2008 that later inspired the Colombian television show, “The Cartel of the Snitches” (El Cartel de los Sapos). Bala fought for Diego Montoya, alias “Don Diego,” who led a rival gang known as the Machos. This private army was set up to fight the Rastrojos, then led by·Wilson Varela, alias “Jabon.” Varela commanded the Calle Serna brothers, until they had him killed in Venezuela in January 2008, most likely with some help from Daniel Barrera. Montoya was arrested in 2007 and extradited to the U.S. the following year. The Norte del Valle Cartel now longer exists, but the return of Patiño has re-ignited old grievances and prompted challenges to the Rastrojos hegemony.

Police have previously denied that the Urabeños are making inroads in the Pacific southwest. But with murder rates steadily rising in Nariño, Valle del Cauca and that department’s capital, Cali, it seems plausible that the violence is partly caused by the Urabeños’ attempted entry into the region, working with Patiño’s men.

According to El Espectador, Patiño is a former cop who learned the geography of the Pacific Coast very well. When he he began working with the Norte del Valle Cartel, he used this knowledge to smuggle cocaine from Colombia’s Western coast, heading operations in the port city Buenaventura.

Patiño turned himself in to police in 1995 but by 1997, he was back on the streets running his drug business again. Five years later, he was arrested again and extradited to the U.S. Now he appears to be back to his old tricks and will use almost three decades of experience to re-establish his criminal empire.