A years-long federal investigation, dubbed "Operation Rhino," traced the route and workings of that pipeline: how and where the men were first approached, how they were radicalized, how they flew to Dubaior Nairobi on round-trip tickets, never to return.

Operation Rhino, one of the largest counterterrorism campaigns since the Sept. 11, 2001, attacks on the United Statesby Al-Qaida, has received attention at the highest levels of U.S.government, including the White House, FBI supervisory special agent E.K. Wilson said this week in an exclusive interview.

The trial of Mahamud Said Omar, a 46-year-old part-time janitor, ended Oct. 18 with a guilty verdict on all five terror-related charges. Omar was the only one of the 18 people charged in the investigation thus far to go on trial. Seven others have pleaded guilty, and six remain fugitives.

Wilsonestimates that the investigation is less than halfway complete.

Three central figures

Operation Rhino formally began in the spring of 2008 and went into overdrive after Minneapolis recruit Shirwa Ahmed died in one of five coordinated suicide bombings in Somalia attributed to Al-Shabab, a U.S.-designated terrorist group there.

Minneapolis FBI agents have traveled around the United States and overseas to assemble pieces of the recruitment puzzle. It's a testament to the close connection between Somaliaand Minnesota, home to the nation's largest population of ethnic Somalis. "There's a saying that when it rains in Mogadishu, the umbrellas go up in Minneapolis," Wilson said.

Most of the young men who left Minnesota to become holy warriors hadn't seen Somalia since they were toddlers, when their families fled at the outset of the 1991 civil war. For that reason, investigators believe that the young men needed indoctrination to get them to go, and help to get there.

"We know now that we were dealing with an organized effort," Wilson said. "To leave the relative comforts of a place like this, you've got to have some external influence, absolutely."

Wilson said the organization had a flat structure, but individuals had specific duties, such as recruitment, fundraising and making travel arrangements.

According to both Wilson and witnesses at Omar's trial, three men proved central to the recruiting effort: Ahmed Ali Omar, 27, the talkative one who kept breaching security by inviting more people into the group; Khalid Mohamed Abshir, 29, the quiet, strong-willed one whose uncle was a member of Al-Shabab in Somalia, and Omer Abdi Mohamed, 27, a good speaker with command of the Qur'an, and the only one now in custody.

At first, these recruiters appealed to the men's sense of nationalism, calling on them to help rout Ethiopian soldiers -- a traditional enemy -- from Somalia. But Wilson said the long-term goal was to radicalize the men as Islamist holy warriors with an agenda of spreading their extremist views across the Horn of Africa.

A plan is hatched

Kamal Said Hassan first learned about a secret plan to join Al-Shabab in the fall of 2007. The former recruit, who fought with Al-Shabab before running away from the group and pleading guilty in the case, testified that Salah Osman Ahmed incited him to join a group of people who were going to Somalia to fight against Ethiopians.

Hassan said Ahmed, who also has pleaded guilty, told him Ethiopians were raping women and burning mosques and houses, and that it was "our duty to go."

It was Omer Mohamed, he said, who did most of the talking at a meeting to plan the trip. Mohamed preached about jihad, and Khalid Abshir also spoke, Hassan said.

During the Muslim holy month of Ramadan, Hassan spent time at the Abubakar As-Saddique mosque in south Minneapolis, even sleeping there with friends, he said. On those nights, Mohamed and Abshir met with the recruits in secret and called for a jihad against the Ethiopians in Somalia. Mohamed argued it was necessary on religious grounds, and Abshir spoke about the nationalistic component, Hassan testified.

"[Mohamed] would recite verses from the Qur'an and verses from the hadith and he would tell us how to interpret what it means," Hassan said in court. The Qur'an is the Muslim holy book, and hadiths are reports of the Prophet Muhammad's sayings and actions.

"Most of the verses he recited were something that had to do with fighting and battles," Hassan said.