Jamal Tarhuni looks over his U.S. passport with his son Rasheed at his home in Portland, Oregon, after returning a month late from a trip to Libya. Tarhuni was denied boarding a U.S. bound flight and summoned for extensive questioning by the FBI.

After the FBI mysteriously interrogated U.S. citizen Jamal Tarhuni in Tunisia and delayed his flight home to Portland by a month, he finally was allowed to return to his family on Feb. 14, as msnbc.com reported. Tarhuni says he still does not know why he was stopped and could not get the FBI to confirm or deny whether he was on the secret no-fly list.

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On Wednesday, the mystery was solved, partially. When Tarhuni, 55, attempted to fly from Portland to Seattle to deliver a presentation about his experience providing humanitarian aid in Libya, he was denied boarding.

His story is familiar to people on the FBI’s secret no-fly list. Tarhuni went to a kiosk at Portland International Airport for automated check in. The machine produced a message saying it could not process his request and instructing him to talk to a customer service representative.

The customer service representative at Alaska Airlines took his driver’s license, then disappeared into another room, he said.

"After about half an hour I was told that for security reasons I would not be able to fly today," said Tarhuni, who was driving to Seattle, about 175 road miles from Portland.

He asked the manager at the airline to contact a representative with the Transportation Security Administration. But after a 10-minute cell phone call, the airline manager said there was no one to resolve the problem.

The no-fly list is maintained by the Terrorism Screening Center, administered by the FBI. According to the FBI web site, the list contains the names of "known and appropriately suspected terrorists." The list has about 20,000 names on it, according to the TSC, including about 500 U.S. citizens. FBI policy prohibits confirming or denying an individual is on the list.

"In practical terms, I have to drive in the snow and rain to Seattle because I made a commitment to the World Affairs Council to give a presentation," Tarhuni said.

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He was scheduled to speak Wednesday evening at a World Affairs Council event on his experience working with Medical Teams International on humanitarian projects in Libya -- which is where he was before his encounter with the FBI in Tunisia.

"Personally I am extremely disappointed, and I am at a loss for what I need to do, and whether justice will be served," said Tarhuni, who was born in Libya but has lived in the United States for more than three decades.

Tarhuni says he will pursue a legal case if necessary to force the government to restore his right to fly. Among other things, he was planning to facilitate teams of American doctors and nurses who will provide training in Libya, which is trying to recover from a civil war and set up a new government after the ouster of longtime dictator Moammar Gadhafi in December.

In the meantime, Tarhuni was preparing to board a train as early as Thursday in Portland to get to a meeting in Minnesota on March 3, where he and a Medical Teams International representative are slated to speak to a Nobel Prize forum.

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