A pair of Iraqi bomb-making experts who boasted about killing American soldiers made it into the United States as refugees because of bungles with background checks — and authorities fear that there could be dozens of similar cases

Waad Ramadan Alwan and Mohanad Shareef Hammadi were allowed to settle in Bowling Green, Kentucky, in 2009 despite having been detained by Iraqi authorities during the war. After a tip-off, investigators discovered Alwan's fingerprints on a phone used to detonate IEDs in Iraq several years earlier — possibly including one that killed four American troops. Both men were arrested after an FBI sting operation caught them trying to ship weapons and cash to al-Qaeda in Iraq, and the two Iraqis bragged to undercover agents about having killed American troops. The pair are now serving lengthy prison sentences. Some 73,000 Iraqis were admitted to the United States for resettlement between 2006 and 2012.