The FBI recently arrested dozens of members of the Mexican Mafia in Los Angeles, aimed at disabling a drug enterprise that was operating largely out of the region’s jails. Federal prosecutors ultimately charged 83 people for racketeering conspiracies, which was said to be a ‘major blow’ to one of the biggest gangs in Southern California, according to U.S. Attorney Nick Hanna.

The raid was the end point of a six-year investigation after the city experienced a crime wave and growth of gang-related murders in 2013. The investigation revealed that plenty of those deaths were related to the drug-smuggling operations in jails, led by Mexican Mafia leadership.

The Mexican Mafia is actually not a Mexican gang – it is wholly a U.S. based prison gang. It is also known as La Eme, and many of its members will tattoo the number 13 on their body. The letter M is the thirteenth letter of the alphabet. Though it is difficult to say for sure, the government claims that there are around 350-400 members in the gang itself, with around 900 associates who help the gang carry out its missions (with hopes to become a full-fledged member at some point).

It was formed in 1957 by thirteen different street gang members across L.A., who – prior to the formation – had warring factions throughout the city. Yet, the gang was notorious because it set aside those differences once members became prisoners. Eventually, violence within the smaller prisons became so bad due to the Mafia that officials decided to transfer some of the leadership to San Quentin to discourage their behavior. This tactic failed.

Over the years, the gang became more organized, violent and powerful. Currently, the Mafia is said to be the controlling organization for nearly every Hispanic gang in southern California, and even holds a loose alliance with the Aryan Brotherhood. Its power extends far beyond prison walls. It is profitable largely because of its vast drug-trafficking network, involving smugglers and up to a third of the ‘take’ on drug transactions across southern California.

The recent indictments connected to the recent raid show how organized and powerful the gang is. According to court documents, members of the Mafia divided up the drug trade to each jail and prison in the state. They imposed ‘taxes’ and if any inmate didn’t follow the gang’s rules, they were subject to violent discipline. At one point, the indictments characterized the Mafia’s conduct as an ‘illegal government’ inside the largest prison system in the country. There is even a prison hierarchy. Surenos are the gang members who are loyal to the Mexican Mafia. Paisas are Mexican nationals without a gang affiliation and Residents are of Latin American descent but also have no prior gang affiliation.

Latino gangs across California writ large are happy to do the bidding of the Mafia – being associated with them and doing their work increases a gang member’s street credit and reputation in Hispanic neighborhoods across the state. This affects crime, drug use and gang activity in each neighborhood of California.

And the power extends beyond other gang members. The indictments assert that gang members used their wives and girlfriends as ‘secretaries’ to transmit orders. Another defendant is a lawyer accused of using attorney-client privilege to pass along messages regarding the gang’s activities.

Law enforcement has struggled with the presence of the Mexican Mafia because it has restructured, using outside sources loyal to the cause to further the increasingly lucrative drug trade and identity fraud. In this way, the Mafia has turned inward, wielding power across the state from behind bars.