Agents of the U.S. Federal Bureau of Investigation are providing support to Mexican authorities investigating last Saturday's murder of three people associated with the U.S. consulate in Juarez, just across the Rio Grande River border from the city of El Paso, Texas. The FBI is also interrogating gang members in El Paso who have ties to a drug trafficking cartel in Mexico.

The focus of the investigation on the U.S. side of the border is a gang called Barrio Azteca, which is affiliated with the Azteca gang that operates in Juarez at the service of the Juarez cartel. The Juarez cartel is at war with the Sinaloa cartel over lucrative drug smuggling routes in the area.

In a VOA phone interview, FBI/El Paso office spokesperson Andrea Simmons says teams of federal, local and Texas state police are detaining and interrogating dozens of Barrio Azteca members in the El Paso area, hoping to gain some information about the murders.

"We are simply doing an intelligence-gathering effort," she said. "We are not certain whether any of these people will have information or are directly tied to anything that happened in Juarez, we are simply trying to get as much information as we can."

Simmons says authorities have arrested some members of Barrio Azteca who were being sought under indictments issued before the Saturday shootings in Juarez. She says there is an expectation that these suspects might know something useful since they are in close contact with their counterparts across the river.

"The gang is considered a transnational gang," she said. "It is almost like they are two brothers. They are the same entity, but they operate differently on the two sides of the border."

Close to 5,000 people have been killed in Juarez in the past two years and it is considered the most dangerous city in the world outside a war zone. Mexican President Felipe Calderon has deployed thousands of military and federal police personnel in the city, but the killings have continued and 96 percent of cases go unsolved.

The situation may change, however, after the murder on Saturday afternoon of two U.S. citizens, one of whom worked at the consulate, and the murder in a separate shooting around the same time of a Mexican man whose wife worked at the consulate. Although investigators say they have found no evidence so far indicating that the victims were targeted because of their consulate associations, some independent analysts think it is a likely possibility.

In addition to the FBI, agents of the U.S. Drug Enforcement Administration and U.S. Customs agents are also working the case on both sides of the border. Andrea Simmons says the agents working in Mexico do so under the authority of the Mexican law enforcement officials conducting the investigation.

"They [Mexico] are a sovereign country and have very different laws from us, so we operate under the authority of the Mexican officials," said Simmons.

U.S. federal agencies are providing technical assistance as well as intelligence that might help solve the murders and, perhaps, help reduce the overall level of violence in the Mexican border city.

"It has been a tremendous effort on everybody's part to try to figure out what happened and hope that solving this case will have a major impact on what is happening in Juarez," she said.

Over 200 local police and federal agents have been conducting raids in El Paso and seeking out known members of Barrio Azteca for questioning. The gang has an estimated 3,000 members in the El Paso area, but investigators are concentrating on around 700 of them. Federal agents are also seeking information on the alleged leader of the gang in Juarez, Eduardo Ravelo, who was placed on the FBI's Most Wanted list last year.