Several dozen suspected terrorist bombmakers, including some believed to have targeted American troops, may have mistakenly been allowed to move to the United States as war refugees, according to FBI agents investigating the remnants of roadside bombs recovered from Iraq and Afghanistan.

The discovery in 2009 of two al Qaeda-Iraq terrorists living as refugees in Bowling Green, Kentucky — who later admitted in court that they’d attacked U.S. soldiers in Iraq — prompted the bureau to assign hundreds of specialists to an around-the-clock effort aimed at checking its archive of 100,000 improvised explosive devices collected in the war zones, known as IEDs, for other suspected terrorists’ fingerprints.

“We are currently supporting dozens of current counter-terrorism investigations like that,” FBI Agent Gregory Carl, director of the Terrorist Explosive Device Analytical Center (TEDAC), said in an ABC News interview to be broadcast tonight on ABC News’ “World News with Diane Sawyer” and “Nightline”.

“I wouldn’t be surprised if there were many more than that,” said House Committee on Homeland Security Chairman Michael McCaul.