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The Hunt for Asiri

Ibrahim Asiri is the son of a former Saudi soldier. The father told a Saudi newspaper his son was radicalized years ago, and fled the county for Yemen. In Yemen, Asiri trained in secret camps, working to perfect his bomb making, and managing to elude capture.

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In November last year U.S. intelligence made capturing Asiri a top priority after the failed printer bomb plot. Those bombs were cleverly disguised inside Hewlett-Packard printers which were being shipped along with clothes and books. Asiri packed the toner cartridge with explosives and added the circuit board of a cell phone--something that did not stand out in state of the art cargo screening.

"We need to find him," John Brennan, President Obama's top anti-terrorism advisor, said at the time.

Before that, U.S. officials say Asiri was believed to be behind the notorious "underwear bomb" worn by then 23-year-old Umar Farouk Abdulmutallab that failed to detonate on Northwest Airlines Flight 253 on Christmas Day in 2009. That bomb contained the same type of explosives as U.S. officials said "belly bombs" would, according to a report by Britain's The Mirror.

ABC News' Martha Raddatz and Nasser Atta contributed to this report.