Early this year, President Obama granted clemency to seven men with ties to Iran, part of a high-profile prisoner swap that left some in federal law enforcement circles seeing red. Among the detainees who won release were men accused of breaking export-control laws by shipping sensitive materials to Iran.

But this month, the Justice Department signaled it remains determined to bring cases over export violations, even if it takes a long while for justice.

Authorities extradited Lim Yong Nam, a citizen of Singapore, to Washington, D.C., to face six-year-old charges that he played a role in a conspiracy to send radio frequency modules to Iran. Federal agents say they traced the serial numbers on those parts to at least 16 unexploded improvised explosive devices they found in Iraq. The discovery prompted a major response from the Department of Homeland Security and the FBI, because about 60 percent of U.S. casualties in Iraq came from explosive devices like them.

Michael Steinbach, executive assistant director of the FBI's National Security Branch, said the challenge for investigators is figuring out when materials that could have a legitimate purpose, such as connecting computers and printers in offices, is actually threatening national security.

"When the material is exported individually," Steinbach said, "it may not look to be anything, but when you start to add up those parts and put together a puzzle, you see those dual use items are for nefarious purposes."

Lim, 42, has pleaded not guilty to the charges and has been ordered detained in Washington. He appeared at the federal courthouse for a brief status conference Monday, when a judge ordered both sides to return next month for an update. His defense attorney, Shanlon Wu, said, "he takes these allegations very seriously and he is anxious to get the case resolved."

The unidentified Minnesota company that made the modules is not accused of wrongdoing. Instead, the indictment said, Lim and other defendants in the case arranged for 6,000 devices to be purchased and sent overseas by misrepresenting that the material would end up in Singapore.

John Carlin, the assistant attorney general for national security, pointed out the allegations still need to be proved in a court of law. But in general, Carlin told NPR, "It's very important to keep technology that can cause the loss of American lives and others out of the hands of those that would do us harm, be they rogue nations or terrorists."

Carlin said people trying to evade export laws sometimes use "deceit and fraudulent documents to create a whole false narrative purposely aimed at throwing investigators off the trial. But I think what this case shows is that ... we are going to prioritize them because of the they can have devastating consequences on our service members and others and with hard work we can figure out who did it and when we do we are going to chase them to the ends of the earth to make sure they're held accountable."

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