The Lebanese-born U.S. Marine who disappeared in Iraq and reappeared in Beirut was flown to Germany on a military plane, leaving a trail of unanswered questions and unrest.

Cpl. Wassef Ali Hassoun, 24, said goodbye to his mother, Halimeh, and his wife, Rana, at the Beirut airport at about 3:30 p.m. Friday, according to family members and U.S. Embassy officials.

"It's out of our hands now," said Elizabeth Wharton, an embassy spokeswoman.

Hassoun arrived at Germany's Ramstein Air Base and was transported by ambulance to Landstuhl Regional Medical Center for a debriefing and an evaluation expected to last several days, before his return to the United States, hospital officials said to reporters.

At the family's apartment in the northern Lebanese city of Tripoli, Hassoun's relatives refused to discuss Hassoun's recent experience or plans, and gave vague answers to questions about his life.

"He left the country, he's safe and that's it," said his brother, Sami, 26, while half a dozen family members sat silently in a salon decorated with a quotation from the Koran and a framed picture of Miami Beach. "We don't want to say anything that he wouldn't want."

It is still uncertain why Hassoun, a translator for the Marines, left his base near Fallujah on June 19, or how he later fell into the hands of a militant group that blindfolded him and threatened him with a sword in a video broadcast on al-Jazeera, the Arab satellite television network. It is also not clear how came to be released and how he made his way from Iraq to Lebanon.

The Pentagon announced that the Naval Criminal Investigative Service is investigating Hassoun's 19-day disappearance.

An official in Lebanon's immigration bureau said the agency had no record of Hassoun's entry to the country, according to the newspaper the Daily Star.

The U.S. Embassy released a statement saying Hassoun "came voluntarily and remained at the embassy while embassy and Department of Defense officials worked out the arrangements for his departure."

On Wednesday, the family denied reports that Hassoun was at home at the Tripoli apartment. On Thursday, relatives refused to confirm or deny his whereabouts until embassy officials announced that Hassoun had arrived at the embassy.

Sami Hassoun told reporters Friday that at a family meeting at the embassy Thursday night his brother "was tense, you could see on his face that he'd been through a lot. But there was a small smile on his face. He was happy to see us."

Hassoun's presence in Lebanon apparently sparked local tensions in Tripoli, where a long-standing dispute erupted in a gunfight Thursday after one man told a member of the Hassoun clan that he came from a family of traitors who collaborated with Americans.

Two people were killed, and Mohamad Said Hassoun was arrested.

On Friday, tension was still high in the area along the Abu Ali River as police, intelligence and military forces surveyed the scene of the shooting. Nearby carpet and perfume shops belonging to members of the Hassoun clan, of whom there are at least 1,000, were shuttered and closed.

Despite anti-American sentiments, some people said they could understand why Hassoun left Lebanon and became a Marine.

"We boycott American products -- I have a Chinese air conditioner, I buy only Lebanese juice," said Moaz Shaaban, a leader in the Sunni Muslim group Tawhid. "But people want to go to the United States for education and jobs."

"Any young guy in Lebanon who could get this kind of work would take it. Anyone," said Mahmoud Hosnein, a taxi driver. "If there were a way for him to work in this country, he would have stayed here."

Mayor Rashid Jammali said Tripoli, the second-largest city in Lebanon, has the country's lowest average monthly income and twice the national rate of emigration.

Hassoun's family is originally from the town of Safira, in the remote Dinniyah mountain region of northern Lebanon. Hassoun's father, Ali Hassoun, 66, once made a living growing and exporting fruit, recalled the father and a family friend.

But his six sons wanted a different life. Wassef Hassoun moved to Utah in 1999 and had little contact with Lebanon afterward, said Ziad Kurdi, 27, a family friend from Safira.

Hassoun joined the Marines in 2001. In Tripoli, the subject of Hassoun's work was so delicate, said Kurdi, that he avoided talking about it. "I didn't bring these subjects up with the family," Kurdi said. "They could get upset."

The ambulance carrying Cpl. Wassef Ali Hassoun drives off the tarmac at Ramstein Air base in Germany.