A key prosecution witness in a Somali terror trial conceded Thursday that he had betrayed the United States and his family when he joined an Islamist terrorist organization, then lied to federal authorities investigating the group.

Under intense cross-examination, Kamal Said Hassan repeatedly admitted that he had lied to federal investigators and a federal judge about the extent of his own involvement and that of certain other Minnesotans.

Hassan, 27, is one of more than 20 Twin Cities men who traveled to their native Somalia in 2007 and 2008 to fight with Al-Shabab, designated by the U.S. government in February 2008 as a terrorist organization. Hassan eventually left the group, returned to the United States and was arrested. He pleaded guilty to conspiring to kill people overseas, providing support to Al-Shabab and lying to federal agents.

Hassan became an undercover informant and cut a deal with federal prosecutors that included his testifying this week in federal court against Mahamud Said Omar, 46, of Minneapolis, who is accused of helping supply men and money from Minnesota to support the Al-Shabab movement in Somalia. The deal reduced Hassan's potential prison time from life to a maximum of 38 years. Hassan testified that he hopes his cooperation will earn him an even lesser sentence.

The bargain also got him and his family members a flight home from Yemen at government expense. The FBI put him and his wife up in a four-bedroom suburban home while he worked undercover for about six months. And federal agents took him to dinner, the movies, the YMCA and bowling, and provided him with a computer and Xbox video games.

To date, 18 people have been charged in the years-long FBI probe -- one of the largest known counterterrorism investigations since the Sept. 11, 2001, bombings. Omar's family and lawyers have maintained that he is innocent and lacked the means and the will to take part in a terrorist pipeline.

As court ended Thursday, Omar turned to some of his supporters, raised his hands over his head and smiled broadly before deputy marshals escorted him back to jail.

Jon Hopeman, Omar's attorney, spent about five hours Thursday cross-examining Hassan. He set the table by tracing the path of Hassan's family members as they fled Somalia's civil war in 1991. Hassan's parents and eight children spent about five years living in a tent in a Kenyan refugee camp before moving to Minneapolis in 1996. The family settled in Plymouth in 2001, where Hassan graduated from Wayzata High School. He attended Minneapolis Community Technical College for two years after that. His entire family became U.S. citizens.

Hopeman noted that Hassan was given an excellent education and a permanent home from which he cannot be deported. "I want to know how you got from there to here, sitting in an orange jail suit in front of a federal judge," he said.

"Well, the first thing, I made a huge mistake by going overseas to fight," Hassan said.

"It was more than a mistake. You became a terrorist, right?" Hopeman said.

"I did, sir."

Hopeman reminded jurors that Hassan's father had interrogated a friend who claimed that he was planning to take Hassan with him on a religious pilgrimage to Saudi Arabia, when they were actually planning in secret to go to Somalia. The friend -- who later went on to become the first known American suicide bomber -- backed down and told the parents Hassan wouldn't be going with him.

"Your dad is a pretty good cross-examiner," Hopeman said. But that didn't stop Hassan, who admitted that he and some other friends later misled his father with a fake itinerary showing him going to Saudi Arabia with a different group. After his father met his friends, he agreed to give Hassan his passport and $700 toward the trip.

But that was a lie, and he and another Minnesota man left the next day for Somalia, where he attended an Al-Shabab training camp and participated in a bungled ambush of Ethiopian and African Union soldiers attempting to restore order in the country.

Hopeman questioned Hassan about numerous lies he told to FBI agents over several months of the investigation and, later, to former Chief U.S. District Judge James Rosenbaum, who accepted his guilty plea.

"You were lying to protect senior members of Al-Shabab, right?"

"No, sir. I'm not doing it to protect them. I'm doing it to protect me," Hassan said.

Hassan confirmed that he never saw Omar at any of the meetings held in the fall of 2007 to plan the secret trips to Somalia. He never spoke with Omar about the plans. He did not see Omar give any money to the travelers. He never saw him at the Al-Shabab training camp or handling a gun, and he never heard him talk about wanting to kill anyone.

Assistant U.S. Attorney William Narus, on redirect, had Hassan confirm that other Minnesota men he did not see at planning meetings or hear talk about traveling to Somalia ended up fighting for or helping Al-Shabab.

Omar's trial resumes Monday.Dan Browning • 612-673-4493 Allie Shah • 612-673-4488