The Washington Post reports that the FBI has found a surprising number of illegal combatants have been found to have previous arrest records in the United States.

In the six-and-a-half years that the U.S. government has been fingerprinting insurgents, detainees and ordinary people in Afghanistan, Iraq and the Horn of Africa, hundreds have turned out to share an unexpected background, FBI and military officials said. They have criminal arrest records in the United States.

There was the suspected militant fleeing Somalia who had been arrested on a drug charge in New Jersey. And the man stopped at a checkpoint in Tikrit who claimed to be a dirt farmer but had 11 felony charges in the United States, including assault with a deadly weapon.

The records suggest that potential enemies abroad know a great deal about the United States because many of them have lived here, officials said. …

As they analyzed the results, they were surprised to learn that one out of every 100 detainees was already in the FBI’s database for arrests. Many arrests were for drunken driving, passing bad checks and traffic violations, FBI officials said.

“Frankly I was surprised that we were getting those kind of hits at all,” recalled Townsend, who left government in January. They identified “a potential vulnerability” to national security the government had not fully appreciated, she said.

The people being fingerprinted had come from the Middle East, North Africa and Pakistan. They were mostly in their 20s, Shannon recalled. “One of the things we learned is we were dealing with relatively young guys who were very committed and what they would openly tell you is that when they got out they were going back to jihad,” he said. “They’d already made this commitment.”