Ex-Soldier Became Contract Killer, Authorities Say His nickname was Rambo. He was a sergeant in the Army, and he trained soldiers to be snipers. But after leaving the military in 2004, the authorities say, he put his skills to work in a less honorable way: earning a living as a contract killer. This past spring, the onetime sergeant, Joseph Hunter, 48, and two other former soldiers agreed to murder an agent of the United States Drug Enforcement Administration and one of that agency's confidential informers, both in Liberia, for a total of $800,000, federal prosecutors said on Friday in Manhattan. The plot had been proposed by men who held themselves out as Colombian drug traffickers, an indictment says. "My guys will handle it," Mr. Hunter wrote in an e-mail on May 30, responding to a question as to whether his team would be willing to carry out the killings, the indictment charges. In fact, the authorities said, the purported drug traffickers were confidential sources for the D.E.A. and part of an undercover sting operation that ultimately led to the arrests of Mr. Hunter and two others: another former American Army sergeant, Timothy Vamvakias, 42, and a former German corporal, Dennis Gogel, 27. All three were charged with conspiracy to murder the agent and the informer, as well as conspiring to import cocaine into the United States. Two other men, Michael Filter, 29, and Slawomir Soborski, 40, who served in the German and Polish militaries, respectively, have also been arrested and charged in the drug trafficking conspiracy, prosecutors said. They are awaiting extradition from Estonia, the authorities said. "The charges tell a tale of an international band of mercenary marksmen who enlisted their elite military training to serve as hired guns for evil ends," Preet Bharara, the United States attorney for the Southern District of New York, said at a news conference on Friday. Mr. Bharara described the charges with Derek Maltz, who heads the D.E.A."s special operations division. Mr. Hunter referred to contract assassinations euphemistically as "bonus work" or "bonus jobs," the indictment says, adding that he told the confidential informers that he had done such work before. Mr. Bharara said Mr. Hunter had successfully arranged for the murders "of numerous people," though he did not name them. The indictment says that Mr. Hunter began collecting résumés for prospective members of his so-called security team, which had planned to use pistols and submachine guns, with silencers, to carry out the murders. Mr. Gogel told one of the drug agency informers that the murders could be made to resemble an ordinary street crime, "like a bad robbery or anything, you know," the indictment says. Mr. Hunter told co-conspirators that they would be working for a Colombian cartel and that they could expect to "see tons of cocaine and millions of dollars," the indictment says. They would also have the opportunity to participate in assassinations, he told them, according to the indictment. "Most of the bonus work is up close ... because in the cities ... you don't get long-range shots," the indictment quotes him as saying. Part of an escape plan involved the use of sophisticated latex face masks that would make the wearer appear to be of another race, the indictment said. Mr. Vamvakias, describing the proposed murders of the D.E.A. agent and the informer, was quoted in the indictment as saying, "You know, we gotta do this, hit it hard, hit it fast, make sure it's done," and then leave. "That's the biggest headache," he added. The job's not the headache; it's getting in and out. Mr. Hunter was taken into custody in Thailand, Mr. Bharara said, and was to be arraigned in Manhattan on Saturday. Mr. Vamvakias and Mr. Gogel were each sent to the United States from Liberia and arraigned on Thursday, when they were ordered detained and entered not guilty pleas, the authorities said. Mr. Vamvakias's lawyer, Bobbi C. Sternheim, said, "We are prepared to vigorously defend" against the charges. Mr. Gogel's lawyer, Edward D. Wilford, declined to comment. The case, with its use of confidential informers posing as drug traffickers, had echoes of other D.E.A. international sting operations, like the one in 2008 that ensnared the Russian arms trafficker Viktor Bout, who was brought to the United States and tried and convicted in 2011. Mr. Bharara and Mr. Maltz made it clear that the drug agency had had its eye on Mr. Hunter for some time. After learning about him through a different investigation, Mr. Bharara said, the agency decided "to do something to incapacitate him." Mr. Maltz said the operation had lasted close to a year. He said the goal was to "be able to take these threats out before something bad happens."