A case against the MS13 operating in El Salvador's capital city shows how the gang's money laundering side is getting more sophisticated, even as it remains reliant on violence for control of its revenue streams.

The Centrales Locos Salvatruchos (CLS) clique of the Mara Salvatrucha (MS13) street gang used extortion proceeds from San Salvador's central market to set up various businesses, most recently a propane gas distribution service, reported La Prensa Gráfica.

The CLS made as much as $50,000 a month from the market, according to El Mundo. This "petty cash," collected and stored in a centralized point, formerly covered expenses such as weapons and drug acquisitions, as well as lawyers' fees.

But managing such a large influx of cash required front businesses, the report said. And it appears that owning breweries, clothing and food stores was not enough for the CLS.

By January 2015, the clique was selling propane to local vendors, after having succeeded in obtaining permits for its company to legally operate and accreditation for its members to become registered gas distributors, the report says.

InSight Crime Analysis

The CLS' propane business is the latest example of how sophisticated the clique's operations had become in the central market. Earlier reports of the CLS' successful takeover of the weapons black market in the area, for instance, signaled the organizational capacity to assert control over a local trade traditionally composed of independent actors.

Despite the clique's sophistication evidenced by these operations -- and mirrored by the MS13 at a macro level both inside and outside of the country -- the CLS still relies on violence to conduct its operations.

Indeed, while criminal sophistication often allows for a less coercive modus operandi, San Salvador's area under the CLS's yoke continues to suffer from outbreaks of lethal violence, due most likely to the high level of territorial control that the clique's criminal activities demand.

A total of 22 security guards were assassinated in the area since September 2013, while violent incidents such as the one that left six dead earlier this year suggest that a latent conflict is playing out between the gang and other criminal actors for control of the extortion and other criminal proceeds.