Mexican authorities have asserted that some of the most infamous drug cartels in the country picked up their violent tactics from a Salvadoran street gang, a dubious claim that may prove to be politically motivated.

On Juy 22, Excelsior reported that, according to officials from the Mexican Attorney General’s Office (PGR), two of the country’s most “dangerous and sadistic” drug cartels — the Zetas and the Beltran Leyva Organization (BLO) — had received training from Central America’s notorious Mara Salvatrucha (MS-13). The paper claims that in the PGR’s response to a public information request, officials maintained that the gang instructed elements of the two cartels in ultraviolent acts like beheadings and mutilations in a bid to help them “terrorize” their rivals. This had resulted in over 5,000 cases involving decapitation and/or dismemberment between 2007 and September 2011.

The report comes amid heightened concern over the street gang’s seemingly rising profile. In March the MS-13 joined its rival gang, Barrio 18, in announcing a bilateral cease fire·in El Salvador, a development which has some analysts worried that both groups are seeking to develop into more mature, organized criminal outfits.

Still, the suggestion that the Zetas and BLO received direct training from the MS-13 is highly questionable. To the extent that Mexican cartels have worked with them at all, existing evidence suggests that the relationship has worked the other way around, with the Mexicans instructing the street gang in larger-scale operations.

In April, for example, officials in Guatemala told the AP that the Zetas had incorporated Guatemalan MS-13 members into their ranks, sending as many as 18 to a training camp in Veracruz, Mexico. After their training the men were allegedly sent back to establish a Zetas-affiliated kidnapping ring in the Central American country.

Yet it should be noted that the very notion of significant contact between the Zetas and “maras” is in itself controversial. As InSight Crime reported at the time, the Zetas/MS-13 story was marked by several factual inconsistencies, and did not seem to match up with the general profile of the Zetas’ operations.

Even if there were evidence of such a relationship, and the MS-13 provided cartel members with direct instruction on methods of violent intimidation (here one imagines the gang delivering grisly workshops on beheading and mutilation techniques), this was probably not organized with the approval of the cartels’ leadership. Both the BLO and Zetas are, after all, motivated by profit. Because media coverage of Mexico’s drug war tends to focus on violent incidents like beheadings and tortures in isolation, it is easy to overlook the fact that these acts are committed with the end goal of acquiring a greater share of the drug market.

In effect, this means that cartel leaders have a strong motivation to limit such bloodshed. They understand that when used selectively, theatrical violence can be an effective intimidation tool against their rivals, but in excess it sparks public outrage and invites a law enforcement crackdown, which is undeniably “bad for business.” Considering this motivation, it seems unlikely that BLO and Zetas heads would seek to model the work of the MS-13, which is not known for its discretion.

The reasoning behind this bizarre and most likely false assertion is unclear. Excelsior does not explicitly name any PGR officials as a source, much less current Attorney General Marisela Morales. Still, the remark’s timing — just three weeks after a presidential election — suggests that it may have been politically motivated.

President-elect Enrique Peña Nieto has said he will take a different approach to combating organized crime than current President Felipe Calderon, vowing to prioritize a reduction in local drug-related violence over the capture of high-level cartel leaders when he takes office in December. As such, the PGR’s claim may have been designed in anticipation of this shift.

The recasting of much of the country’s recent drug violence as “un-Mexican” definitely favors Peña Nieto, as it moves the current debate away from the power on domestic drug cartels and towards a broader discussion of excess violence. In another apparent overture to the president-elect’s proposed change in focus, Attorney General Morales herself stressed on July 23 that local small-time drug dealing, as opposed to transnational trafficking, is a major contributor to violence in the country.

However, while pushing the blame for Mexican cartel violence to Central America’s maras may be politically advantageous, evidence is lacking.