Home from what he calls the "wilds" of Afghanistan, Pittsburgh FBI Chief Division Counsel Jeff Killeen climbed into a colleague's car at the airport for the ride to the South Side office.

As Agent Bill Crowley drove, he noticed something different about his friend.

In addition to being 10 pounds lighter, Agent Killeen was a bit twitchy, glancing over his right shoulder and looking out the window as if he expected to see something bad.

Turns out he was.

Out of reflex, he was checking for suicide car bombers -- the main threat to any American on the chaotic roads of Kabul.

"Crowley said that I was 'on edge,' " said Agent Killeen, 56. "You're constantly looking for threats over there."

The jumpiness has worn off since that day in late November.

But Agent Killeen, a supervisory agent and 14-year veteran of the Pittsburgh office, would gladly return to the Afghan capital, where he spent nearly five months investigating war profiteering as part of the International Contract Corruption Task Force.

"Afghanistan has always piqued my interest," he said. "To me, it was a great opportunity. If someone said you have to go back in 10 minutes, I'd say I'll do it in five."

Duty in Kabul inspires many federal agents because the terror attacks of Sept. 11, 2001, were carried out from Afghanistan and al Qaida leader Osama bin Laden is still believed to be hiding in the mountains near the Pakistan border.

The link to 9/11 is direct, and for Agent Killeen, so are the consequences of a U.S. failure to tame the insurgency that threatens Kabul from all sides.

"If this place is abandoned to the Taliban," he said, "it will foster a potential return for terror groups to train and possibly do a repeat of 9/11."

While he described the country as "a mess," he was gratified to be part of an effort to restore stability by cracking down on massive fraud by U.S. and Afghani contractors.

FBI agents from around the country are pulling voluntary four-month rotations on the task force, working with the Department of Defense, U.S. Agency for International Development and other agencies.

Packed into rooms near the U.S. embassy compound, surrounded by suicide bombings, shootings and the occasional 4 a.m. rocket attack nearby, agents piece together the paper trail of billions of dollars worth of contracts awarded for roads, power plants and other projects while seeking evidence of fraud.

Afghanistan, a country battered by war and poverty for generations but now flush with U.S. and foreign aid, has become a land of bribery and bid-rigging.

"It's just a way of life," said Agent Killeen. "It's endemic in modern Afghanistan. It's absolutely pervasive. When I was there I saw it first-hand."

Dozens of complex white-collar cases are in the pipeline for prosecution in the U.S. courts. These investigations often take years to develop and most have yet to reach the indictment stage.

But one notable case that has received public attention in the United States involves a Houston security company, United States Protection and Investigations LLC, indicted in October on charges of fraud and conspiracy.

Federal prosecutors said the company owners in Houston, Barbara Spier and her husband, Dwayne Spier; their operations manager in Afghanistan, William Felix Dupre, of North Carolina; and executive assistant Behzad Mehr stole $3 million from the U.S. government.

Agents said Mr. Mehr fabricated invoices from rental and fuel companies in Afghanistan while the company created false documents to inflate expenses for employing security personnel from the Afghan Ministry of Interior.

The Spiers and Mr. Dupre used the false documents to get reimbursed by USAID, according to the indictment.

Another big case playing out in federal court in Chicago shows that the military itself is sometimes part of the problem.

In August, two U.S. servicemen were charged with accepting nearly $100,000 in bribes to arrange defense contracts for Afghani companies at Bagram Airfield.

Agent Killeen, who helped wrap up loose ends for the Houston investigation, said he's not allowed to talk about pending prosecutions.

But he said the kind of fraud perpetrated in those two cases is business as usual in Afghanistan, Iraq and Kuwait, where the task force also operates.

So many Afghanis are trying to grease palms that someone, somewhere is likely to take the bait.

"If you put out enough lines you're going to catch a fish," he said of U.S. personnel accepting payoffs. "There is so much money over there."

Working white-collar fraud cases in Afghanistan, however, isn't quite the same as doing it in, say, Pittsburgh.

Before he left, Agent Killeen spent two weeks training at FBI headquarters in Quantico, Va., practicing such skills as "getting off the X" -- or learning to recognize threats quickly enough to escape.

Much of the course involved evasive driving to avoid being boxed in on choked roadways, since most of the danger in Afghanistan is on the roads.

Quantico trainers also gave agents a copy of "The Gift of Fear," a 1998 best seller by security specialist Gavin de Becker that instructs readers to trust their instincts in realizing when violence is about to erupt.

Agent Killeen also made sure he was in top shape, a requirement of all the agents heading overseas. That wasn't a problem for the self-described "workout-aholic" who hits the gym in the FBI building almost every day.

He found the training paid off, too, because in the streets of Kabul he carried about 60 pounds of gear, including emergency medical equipment, flak jacket, M-4 assault rifle, 200 rounds of ammo and a sidearm.

Fitness may have also helped him deal with 16-hour workdays and what agents call the "Kabul Crud."

After about eight days in the country, many Americans get sick from the swirling dust, the lack of sanitation and the strange food. While parts of Kabul are modern, areas on the outskirts and in the mountains are almost medieval.

"We called it the Day 8 Syndrome," he said. "It's just a question of how sick you're going to get."

Liberal doses of Cipro, a powerful antibiotic, kept most of them on their feet, including Agent Killeen. But some American personnel were laid up for days or weeks.

The hostile environment also presented a challenge in how agents did their jobs.

Often they would head out into the city of 5 million people to track down leads, gather business records and interview Afghani businessmen with the help of an interpreter. Agent Killeen speaks Russian and German but not Dari, the main Afghan language.

But few streets are named. People tend to say they live near some landmark, such as a police station, but without an address it can take all day to find a building or an individual.

"That was a difficulty -- just trying to find people," said Agent Killeen. "Sometimes, if you ran down one lead in a day that was a good day."

Agent Killeen, whose resume includes stints as a street agent in Minneapolis and working counter-intelligence cases in New York City, has been in dicey situations before, but in Kabul he said he felt a constant uneasiness.

He lived with another agent in a Conex Box -- essentially a temporary trailer -- near the embassy and was regularly subjected to "duck and cover" rocket attacks nearby.

Outside the wire, he traveled alone with his partner in an armored vehicle and encountered guards carrying AK-47s outside nearly every government building and business. In addition to the Afghan army and local police, many businessmen employ armed bodyguards.

Yet as dangerous as Kabul is, no FBI agents have been killed there or in Iraq. For Agent Killeen, the irony is that a fellow agent did die during his tour -- in Pittsburgh.

The day before he left Afghanistan, Agent Sam Hicks was shot to death during a drug arrest in Indiana Township.

Christina Korbe, 40, has been charged with second-degree murder and other offenses in the slaying.

As chief counsel for the FBI's Pittsburgh division, Agent Killeen has been contributing to that investigation. Agent Hicks, who had often stopped by his office to seek advice, was the first Pittsburgh FBI agent to die in the line of duty.

"I would figure that it was much more likely to have a fallen agent in a war zone, rather than in suburban Pittsburgh," he said. "That's tough to grasp."