ATLANTA, Georgia (CNN) -- They prefer the darkness and calm of early morning when their targets are most vulnerable, still sleeping or under the influence. They make sure their prey -- suspected killers and other violent fugitives -- know what they're up against.
U.S. Marshal supervisory inspector James Ergas takes aim during a computer-simulated attack.
"When they wake up to a submachine gun and flashlight in their face, they tend not to fight," says James Ergas, the supervisory inspector for the U.S. Marshals Southeast Regional Fugitive Task Force.
The U.S. Marshals Service is the nation's oldest law enforcement agency and best known for protecting federal judges, transporting federal prisoners and protecting witnesses. Less known is the cutting-edge work of the agency's six regional task forces in capturing suspects.
The task force in Atlanta is located in a nondescript warehouse office park. In 2007, the investigators from the Southeast task force arrested more than 3,000 suspects; only once did the Marshals exchange gunfire, Ergas says. Watch Ergas blast bad guys in simulated attack »
"This is the crème de la crème of the Marshal Service," says Eugene O'Donnell, a former prosecutor and New York City police officer who now teaches at the John Jay College of Criminal Justice in New York.
On any given day, Ergas and his force are tracking 10 to 15 suspected killers roaming the Southeast, while also searching for other violent offenders. Already this year, they have been involved in a number of high-profile searches: Gary Michael Hilton, the suspect charged in the killing of Meredith Emerson who disappeared while hiking in northern Georgia; a fugitive Marine wanted in connection with the killing of Lance Cpl. Maria Lauterbach in North Carolina; and suspects wanted in connection with the killings of two suburban Atlanta police officers.
But most of the time they're chasing suspects outside of the glare of the media spotlight.
"Our mandate is to track violent fugitives -- murderers, armed robbers, rapists and fugitives of that caliber," says Keith Booker, the commander of the task force. Watch Booker describe their mission »
One suspect currently being hunted is Charles Leon Parker who has been on the run since the 1980s after being accused of molesting his stepdaughters. The Marshals were brought in recently, Booker says, after Parker allegedly called one of his victims and said, "I wanted you to know I saw you and your daughter, and she sure is beautiful."
O'Donnell says it takes highly trained, high energy, "really special people" to do such work day in and day out, especially when they're up against "some of the most dangerous individuals in the country."
"It's not an exaggeration to say they're the front of the front line," O'Donnell says. "It's not going to get any more challenging than this in law enforcement."
To make sure they are well prepared, the Atlanta office is equipped with a locker full of high-powered weaponry; a high-tech operations center, complete with flat screen TVs, where they communicate directly with investigators in the field; a two-story house for training; and a 300-degree computer simulator that puts the Marshals into real life danger scenarios.
In one demonstration, Ergas steps into the simulator and responds to reports of shots fired at a workplace. A woman rushes to a victim on the ground, as Ergas barks out commands. Moments later, a man rounds the corner. He too tends to the victim. Suddenly, the gunman runs into the corner and Ergas opens fire with his Glock. The suspect hits the ground. Watch Ergas say there's no better training than the simulator »
A split second later, another gunman emerges, and Ergas blasts him too. Think of it as Wii on steroids.
"These are things you cannot get on a range," Ergas says.
There are 50 different scenarios the simulator can create, with a technician able to change each scenario. A trainee can use a shotgun, rifle, Glock 22 or Glock 23. The guns shoot a laser and each shot is traced. Sometimes, the simulator jams the guns to see how one responds to the situation.
After each training session, the person is debriefed about why he or she opened fire or didn't fire at all. Each shot is analyzed, because in the real world a law enforcement officer is held accountable for every bullet that comes out of his or her gun.
It helps investigators train for situations they could face on any given day, at any given moment, Ergas says.
"No one wants to shoot anyone," Ergas says. "Even officers that may not have pulled the trigger will be affected by shooting and killing someone."
O'Donnell says the fact the task force rarely engages fire with suspects and that they have such rigorous training, "underscores you can teach tactics."
"This is a model," he says.
Booker says it helps having a coordinated team of armed officers with shields and big guns, as well. "We overwhelm them with surprising speed and force," he says. "That's what keeps us safe, and that's what keeps them safe."
His message for those still out there?
"We'll pull all of our collective knowledge and resources and investigative techniques to hunt them down and take them into custody," Booker says. "We won't stop until our job is finished." E-mail to a friend