Top U.S. Officials Mourn Slain ICE Agent Jaime Zapta, Promise Justice

'We will not relent, or flinch, or let up in any way,' said Napolitano.

Feb. 22, 2011— -- Three of the nation's top law enforcement officials today eulogized slain U.S. special agent Jaime Zapata, who was gunned down in Mexico last week and they pledged that his killers would be brought to justice.

"The U.S. and Mexico will bring the long, hard arm of the law down on Jaime and Victor's shooters," said an emotional Immigration and Customs Enforcement Director John Morton, addressing Zapata's parents at the funeral in Brownsville, Texas.

Zapata and fellow agent Victor Avila were returning to Mexico City from a training exercise in Monterrey when their armored SUV with diplomatic plates was chased off the road and later sprayed with gunfire. No arrests have been made in the case.

"Together we will continue to see that Jaime and Victor's work is done and that the rule of law triumphs over lawlessness and empty violence," Morton said. "My friends: no retreat, no compromise. Our cause is just, our cause is right. There is no other way."

Homeland Security Secretary Janet Napolitano said, "We will not relent or flinch or let up in any way in our determination to see that those responsible for his death will be held responsible for their crimes."

Alluding to the violent drug cartels believed to have ties to the attacks, Attorney General Eric Holder vowed officials would "eradicate the scourge" that led to Zapata's death. "That is how we will honor Agent Zapata, that is how we will pay tribute to him. And that is how we will ensure that his spirit will live on," he said.

The presence of three top Obama administration officials at Zapata's funeral underscores the seriousness of the attack, which was the highest-profile Mexican incident involving a U.S. government agent in more than 20 years.

It also reflects a growing concern by law enforcement chiefs that U.S. agents may be becoming targets.

Investigators believe the Mexican assailants likely knew their targets were U.S. officials before unleashing their attack, though it remains unclear whether the shooting was premeditated.

Accounts of the incident provided by several government sources suggest that Zapata and Avila became targets after going through a toll plaza on a rural highway outside the town of Santa Maria del Rio.

They were chased by two vehicles, which then forced the agents off the road. At least one of the suspects then approached the Americans' SUV and engaged the ICE agents, who are believed to have been unarmed.

It is unclear what the men said to each other, but U.S. officials, who requested anonymity because the investigation is ongoing, said the agents clearly identified themselves as diplomats. Shortly after that, they were engulfed in a hail of gunfire.

Zapata was killed and Avila was hit twice in the leg. He attended the funeral of his colleague today in a wheelchair.

Pressure on Mexican Cartels

The FBI is leading a special joint task force between the Department of Homeland Security and Department of Justice in an effort to catch the assailants, with several officers on the ground in Mexico actively supporting the investigation.

While officials have not publicly discussed a possible motive, there is speculation the attack was tied to raging drug-related crime across Mexico that has left 35,000 people dead since December, 2006.

The state of San Luis Potosi, where the attack occurred, has experienced occasional outbursts of violence as cartels have battled for territory and used aggressive tactics to steal cash, weapons and vehicles.

Texas missionary Nancy Davis was shot and killed last month in northern Mexico while driving a Chevrolet pickup truck which investigators believed the attackers wanted to steal. The U.S. special agents' blue Suburban might have been a similar target.

If the agents were ambushed, it could signal a reaction to stepped-up pressure by U.S. and Mexican authorities on cartel activities.

The U.S. has pledged $1.4 billion to help equip and train Mexican law enforcement to combat the cartel-fueled violence in recent years.

And in the past two years alone, officials have seized $282 million in illegal currency, 7 million pounds of illegal drugs, and 6,800 illegal weapons flowing between the U.S. and Mexico, representing significant increases over prior years.

"As they see that U.S. involvement grows more and more and more, the temptation on their part to start going after Americans will also grow," said former Mexican Foreign Minister Jorge Castaneda, referring to the cartels.

Zapata's murder is the highest-profile Mexican incident involving a U.S. agent since the kidnapping, torture and murder of undercover Drug Enforcement Administration agent Enrique Camarena in 1985.

Zapata, 32, was a four-year ICE veteran based in Laredo, Texas, and Avila, was a six-year ICE veteran based in El Paso, Texas. Both men had been stationed at the U.S. Embassy in Mexico City as part of a human smuggling and border security enforcement task force.