Updated 4:34 p.m. ET
A top drug gang enforcer says he ordered the killing of a U.S. consulate worker because she helped provide visas to a rival gang in the border city of Ciudad Juarez, federal police said Friday.
Jesus Ernesto Chavez, whose arrest was announced on Friday, leads a band of hit men for a street gang tied to the Juarez cartel, said Ramon Pequeno, the head of anti-narcotics for the Federal Police.
Pequeno said Chavez ordered the March 13 attack thatas they drove through the violent city toward a border crossing to the U.S. Pequeno said Chavez told police that Enriquez was targeted because she helped provide visas to a rival gang.
The suggestion that drug gangs may have infiltrated the U.S. diplomatic mission runs counter to previous statements by U.S. Embassy officials that Enriquez was never in a position to provide visas and worked in a section that provides basic services to U.S. citizens in Mexico.
And U.S. officials who looked into the possibility of corruption involving Enriquez shortly after her killing found no evidence that she was involved in illegal activity at the consulate, said a federal official in the U.S. who is familiar with the investigation. The official spoke on condition of anonymity because he was not authorized to speak about the case.
He said the motive behind the attacks remains unclear to U.S. officials.
"The 'why' has not been answered" in the killing of Enriquez, her husband and the husband of a co-worker, the official said.
The attack on Enriquez - within view of the Texas border - and a nearly simultaneous attack that killed the husband of a Mexican employee of the consulate raised concerns that Americans and U.S. government personnel were being caught up in drug-related violence.
Enriquez was four months pregnant when she and husband Arthur H. Redelfs, were killed by gunmen who opened fire on their vehicle after the couple left a children's birthday party. Their 7-month-old daughter was found wailing in the back seat.
Jorge Alberto Salcido, the husband of a Mexican employee of the consulate, also was killed by gunmen after leaving the same event in a separate vehicle.
President Obama expressed outrage over the killings at the time, and Mexican President Felipe Calderon said he was indignant and promised a swift investigation.
Chavez told police that gunmen opened fire on Salcido because the two cars were the same color and the hit men did not know which one Enriquez was in, Pequeno said.
Investigators also have looked at whether Redelfs may have been targeted because of his work at an El Paso County Jail that holds several members of the Barrio Azteca, believed to be responsible in the attacks.
In March, U.S. federal, state and local law enforcement officers swept through El Paso, picking up suspected members of the gang in an effort to find new leads in the killings.
A suspect detained in Mexico shortly after the shooting confessed to acting as a lookout as the Azteca gang supposedly hunted down Redelfs, but he was never charged and was released without explanation.
Officials also have speculated that both attacks could have been a case of mistaken identity.
Pequeno said Chavez belongs to Barrio Azteca, which works for the Juarez cartel on both sides of the border.
The Juarez cartel's turf war against the Sinaloa cartel has made Ciudad Juarez one of the deadliest cities in the world. More than 2,600 people were killed last year in the city of 1.3 million people across the border from El Paso, Texas.
Mexican police say Chavez also confessed to participating in the Jan. 31 killing of 15 youths at a party that was mistaken as a gathering of drug-gang rivals. That massacre fueled outrage over innocents killed since Calderon launched an all-out offensive against drug gangs in 2006. More than 23,000 people have been killed in Mexico's drug related violence since then.
Mexico's central intelligence database says the 41-year-old suspect served five years in a Louisiana prison on drug distribution charges. Chavez was detained in Mexico in 2008 by the Mexican army on drug trafficking allegations and released, only to be promoted within the Azteca gang, Federal Police said.
Chavez was arrested along with five suspected gang associates who are accused of carrying out killings or providing support. Six assault rifles, a sub-machinegun and ammunition were seized.
Also on Friday, Mexican officials were investigating a gun battle between rival drug and migrant trafficking gangs near Mexico's border with Arizona thatand at least six others wounded.
Sonora state prosecutors say the fire fight on Thursday took place in a sparsely populated area about 12 miles from the Arizona border, near the city of Nogales. The area is considered a prime corridor for migrant and drug smuggling. All of the victims were believed to be members of the gangs.
Several U.S. citizens have been killed in Mexico's drug war, most of them people with family ties to Mexico. It is very rare for American government employees to be targeted, although assailants hurled grenades at the U.S. consulate in the northern city of Monterrey in 2008.
Civilians have increasingly gotten caught in the middle of drug gang violence that has made Ciudad Juarez one of the deadliest cities in the world, with more than 2,500 people killed last year alone. At least 11 people were killed in Ciudad Juarez over the weekend.
The three died during a particularly bloody weekend in Mexico, with nearly 50 people killed in apparent gang violence. Nine people were killed in a gang shootout early Sunday in the Pacific resort city of Acapulco, one of Mexico's spring break attractions.
The State Department has authorized U.S. government employees at Ciudad Juarez and five other U.S. consulates in northern Mexico to send their family members out of the area because of concerns about rising drug violence. The cities are Tijuana, Nogales, Nuevo Laredo, Monterrey and Matamoros.
Nearly 18,000 people have been killed since Calderon deployed tens of thousands of troops and federal police across the country in December 2006 in an offensive against drug traffickers.
In Acapulco, a battle between drug gangs killed eight gunmen and a 23-year-old woman caught in the cross fire as she rode in a taxi, according to a Guerrero state police report.
Weekend shootouts left more than 30 people dead in Guerrero, where several cartels are battling for drug dealing turf and trafficking routes. Eight people were killed Friday night when gunmen burst into party in western Sinaloa state.
Gangs often fight for control of trafficking routes, abducting migrants from each other.
Gang violence near the Arizona border has led to calls from officials in the U.S. state for greater control of the border and is one reason given forpassed in April requiring Arizona police to ask people about their immigration status in certain situations.