An alliance between the Zetas cartel and Mara Salvatruchas street gang will pose a major challenge for law officers who are battling the Mexican drug cartels, experts say.
"It's not good for anyone. It would be 'the mother of all mergers' involving two of the most violent gangs we know of," said Phil Jordan, former director of the El Paso Intelligence Center. "The Zetas are definitely extending south, but the $64,000 question is why south instead of north where the money is?
"Part of it may be that the cartels have lost a lot of manpower in the drug cartel wars, and they are turning to the gangs. We know that they have recruited women to operate as 'sicarias' to carry out hits, and to handle some of the other work."
A war of attrition by drug organizations has left more than 50,000 people dead in Mexico during the past five years -- about 9,500 in Juárez.
The Aztecas and Barrio Aztecas are the dominant gangs in Juárez and El Paso, respectively, and are allied with the Carrillo Fuentes drug cartel. Two of their rival gangs in Juárez, the Mexicles and Artistas Asesinos, work with the Joaquin "Chapo" Guzman organization. Those two factions are thought to be responsible for the thousands of killings that have occurred in Juárez since 2008 as they fight for control of the Juárez drug-running corridor.
Meanwhile, the south Texas-northeast Mexico drug corridor is controlled by the Zetas, which included former Mexican elite soldiers and is thought to be trying to expand its control in Mexico.
Authorities in Guatemala recently disclosed that the Zetas, a Mexican transnational criminal organization, recruited Mara Salvatruchas (also called Maras and MS-13) in Central America to help them. This merger brings together two highly mobile and brutal gangs, experts said.
El Paso police Sgt. Chris Mears said the U.S. border law enforcement community is prepared to repel any intrusions by such an alleged alliance.
"We're always monitoring criminal organizations, and the Zetas, who mostly operate south of the border, have not affected us in El Paso," Mears said. "But if they were to show up here, we are prepared."
According to The Associated Press, an official in Guatemala said the Zetas are providing Maras with military training and indoctrination in Mexican camps.
Mexican officials have dismantled Zetas training camps in the state of Nuevo Leon, but they declined to comment on the Guatemalan claims, the news agency reported.
Rob Gallardo, a veteran youth gang expert and founder of Operation No Gangs, said the partnership may be tenuous.
"The idea of 'tying rags,' as such alliances are called, are usually done for a defined purpose and for a defined time," Gallardo said. "Such groups are competitive and distrustful of one another.
"These groups today are far more sophisticated than the gangs of the past. For example, they use satellite telephones and have access to the Internet. They can communicate even if they don't have visitors in prison."
U.S. federal law enforcement agencies are familiar with the Zetas and Maras. In its "National Threat Assessment" on the Maras, the FBI said "this mobile street gang ... could be operating in your community now or in the near future."
The Maras, which began as a prison gang in Los Angeles, grew after members were deported to their home countries in Central and South America and in Mexico.
The FBI said the Maras operate in at least 42 U.S. states and the District of Colombia and engage in such crimes as drug distribution, murder, rape, prostitution, robbery, home invasions, immigration offenses, kidnapping, carjackings, auto thefts and vandalism.
"Most of these crimes, you'll notice, have one thing in common -- they are exceedingly violent," the FBI said.
Retired law enforcement officers Ramon Montijo and Richard Valdemar, experts on gangs and drug cartels, said both Zetas and Maras are highly dangerous groups.
"The Zetas were involved in SWAT-styled kidnapping and murder in Phoenix in 2008," said Montijo, a former Los Angeles Police Department investigator and former police chief of Bernalillo, N.M., and of Greenfield and El Centro in California. "They've recruited former Kaibiles, who were the military elites during the civil war in Guatemala.
"I've been trying to tell our law enforcement people to wake up because some of these gangs are already here," he said.
Montijo does presentations throughout the United States and in other countries for law enforcement groups.
"You have to understand the mentality of these gangs. For some of them, it's considered an honor to kill a policeman, especially in the United States," he said.
Montijo said the Zetas have military training and are highly disciplined.
Last year, Mexican authorities said that Zetas were suspected of shooting at two U.S. Immigration and Customs Enforcement agents, killing one of them.
"I once met a Zeta who used to be a striker (a member of a high-tech unit) with the U.S. 101st Airborne Division," Montijo said. "The Zetas will do you in if you use the drugs they sell. They don't like any loose ends."
In November, U.S. authorities charged five members of an alleged Zetas cell in Chicago and accused them of transporting millions of dollars in drug proceeds between Chicago and Mexico.
Zetas also were implicated in arms-smuggling between Dallas and El Paso-Juárez.
Valdemar, who's investigated drug corruption in California, said a Zetas-Maras alliance could simply provide a bigger army for someone else.
"We've seen this in brokered peace treaties involving other gangs that did not turn out well," Valdemar said. "Sometimes we forget that their business -- the gangs -- is criminal in nature."
Like Montijo, Valdemar said he, too, is concerned that dangerous gangs are making inroads in the United States.
"One of the cartels killed a policeman in Salt Lake City, but most people elsewhere haven't heard about that," said Valdemar, a former law enforcement investigator in California who witnessed the evolution of gangs like the Bloods, the Crips, the 18th Street Gang and others.
Another way that drug cartels become more powerful is by taking over the areas of influence created by power vacuums.
For example, U.S. and Mexican authorities agree that they were successful in coordinating the efforts that dismantled the Arellano Felix cartel based in Tijuana, but that also created an opening for newcomers to fight for control.
Stratfor, a geopolitical analysis company in Austin, recently reported that Mexican officials have made progress against the "Chapo" Guzman cartel by killing or arresting key leaders who handled arms trafficking and finances for the organization. This may have emboldened the Zetas to expand into Guzman territory.
"Los Zetas have a presence in more territories than the (Guzman) Sinaloa Federation, which operates in fewer states now than it did it 2005," Stratfor said in a 2012 report. "Durango, Jalisco and Sinaloa are traditional areas of Sinaloa control in which Los Zetas are trying to establish a presence."
The Zetas began as an enforcement arm of the Gulf cartel in Tamaulipas, but they broke away later to become an independent transnational gang.
Valdemar said he expects that the next president of Mexico will probably enter a peace treaty with the drug cartels "to reduce the violence and stop their growth."
Mexico will elect a new president in July.