McALLEN -- The sister of a federal agent wounded in an attack in Mexico says she hoped the lawsuit filed this week by her brother and the family of an agent who was killed will force the government to answer their questions.Jaime Zapata and Victor Avila, U.S. Immigration and Customs Enforcement agents, were attacked on Feb. 15, 2011, in their armored sport-utility vehicle near San Luis Potosi, Mexico, shortly after picking up equipment from another agent.Zapata died, and Avila was seriously wounded.The lawsuit filed Tuesday in federal court in Brownsville names nearly two dozen defendants, among them the agents' supervisors, the company that armored their vehicle and gun shops that reportedly sold two of the weapons used in the attack.The suit asserts that Zapata and Avila never should have been sent on the dangerous mission, their armored SUV was flawed, and at least two of the guns used against them were bought in the United States and eventually smuggled to Mexico."The complaint really is seeking accountability for those people to come forward and not let this happen again," said Magdalena Villalobos, Avila's sister.The government has not answered many of the families' questions in the two years since the attack.Zapata and Avila had driven from Mexico City to San Luis Potosi to pick up equipment from another agent from the Monterrey office. Shortly after beginning their return trip, the pair was ambushed by armed men.Zapata parked the vehicle, but when he did so the automatic door locks unlocked. Gunmen pried open the door and in their struggle to close it, the agents partially lowered a window, which allowed their attackers to fire inside.BAE Systems, a U.S. subsidiary of the U.K.-based global defense contractor that outfitted the armored Suburban, is named in the lawsuit. The case accuses BAE of negligence in not deactivating the feature that automatically unlocks the doors.Brian Roehrkasse, spokesman for BAE Systems, said Wednesday the company had not yet been served with the lawsuit."We are evaluating the allegations and have no comments at this time, except to note that we are not the vehicle manufacturer and do not make the door locking mechanisms," he said in an email.The suit names four of the agents' supervisors and says they were negligent for putting the agents in harm's way.The highway that Zapata and Avila traveled on "was known to be patrolled and controlled by a dangerous criminal organization," the lawsuit said. Less than a month before, the U.S. government had sent a notice to all U.S. embassy employees that there was a travel restriction in place and they should not travel in the prohibited areas."Despite opposition by Avila and despite having full knowledge of the dangers present with the package pickup, Mexico supervisors instructed Avila and Zapata to proceed with the directive," according to the lawsuit.A diplomatic courier service could have moved the equipment securely rather than sending two unescorted agents to get it, the lawsuit said.Barbara Gonzalez, an ICE spokeswoman, said the agency doesn't comment on pending litigation as a matter of policy."The U.S. Immigration and Customs Enforcement family continues to mourn the loss of Special Agent Zapata," Gonzalez said. "We honor his sacrifice and those of his brothers and sisters in the law enforcement community who have perished in the line of duty."Julian Zapata Espinoza, is charged with murder and attempted murder charges in federal court in Washington, D.C.Zapata Espinoza is a reputed member of the Zetas cartel who, Mexican authorities say, mistook the agents' Suburban for a rival's vehicle.The suit says some of the weapons used in the attack made it to Mexico even after federal investigators had opened an investigation. Several people from the Bureau of Alcohol, Tobacco, Firearms and Explosives are named.