ALEXANDRIA, Va. -- A judge is scheduled to hear arguments on the constitutionality of the government's no fly list in a case now embroiled with allegations of terrorism against a one-time northern Virginia resident.

For four years, the government has tried unsuccessfully to get a judge to toss out a lawsuit filed by Gulet Mohamed of Alexandria. He says he was unfairly placed on the no-fly list.

At a hearing Friday, the government will again ask that the case be dismissed, arguing in part that defending the lawsuit would require it to divulge state secrets.

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The case took a twist Thursday when the FBI announced that Gulet Mohamed's older brother, Liban, has been placed on the bureau's list of most wanted terrorists.

Gulet Mohamed's lawyer says the timing of that announcement is meant to influence the judge.

The FBI said Thursday that Liban, a former taxi driver, was a recruiter for the al-Shabab terror group in Somalia.

An arrest warrant, originally issued in February, was unsealed Thursday in U.S. District Court in Alexandria for Liban Haji Mohamed, 29, a naturalized U.S. citizen born in Somalia.

The attorney representing the younger Mohamed, Gadeir Abbas, told The Associated Press on Thursday that Liban aggressively advocated on his younger brother's behalf when Gulet Mohamed was detained in Kuwait several years ago and barred from returning to the U.S., and that the FBI began to harass Liban as a result. He said his family suspects he went into hiding to avoid the harassment.

"Al-Shabab has killed Liban's uncle and imprisoned his cousins," Abbas said. "His family believes the allegations have no basis in fact."

FBI spokeswoman Lindsay Ram said in an email late Thursday that the FBI had no comment on Abbas' allegations.

Liban Mohamed is charged with providing material support to al Qaeda and al-Shabab. Additional court records detailing the charges against him in federal court remained under seal Thursday.

He is now one of 31 people on the FBI's list of most wanted terrorists.

The FBI says it believes Liban Mohamed left the U.S. in July 2012 for east Africa. He lived in the Alexandria area of Fairfax County prior to that, working as a taxi driver. The FBI says he is a key target because his knowledge of the nation's capital could help al-Shabab plot an attack here.

"It is important for us to locate Mohamed because he has knowledge of the Washington, D.C., area's infrastructure such as shopping areas, Metro, airports, and government buildings," said Carl Ghattas, special agent in charge of the Counterterrorism Division at the FBI's Washington Field Office. "This makes him an asset to his terrorist associates who might plot attacks on U.S. soil."

The FBI is offering a $50,000 reward for information leading to Liban Mohamed's arrest and conviction.

The agency also said Liban Mohamed is a "close associate" of Zachary Chesser, an American who made online death threats to the creators of "South Park" for mocking the Prophet Muhammad. In 2010, Chesser was arrested and charged with offering himself as a fighter to al Shabaab.

Abbas said the timing of the FBI's announcement about Liban was an attempt to influence a judge to toss out the lawsuit that Gulet Mohamed filed against the government.

"We would question the timing of the FBI's placement of Liban on the most-wanted list on the day before a major hearing on the government's authority to maintain the no-fly list," Abbas said in a telephone interview.

Gulet Mohamed, an Alexandria resident and also naturalized U.S. citizen, was 19 when he was detained by Kuwaiti authorities in 2011. He has said that he was beaten and interrogated at the behest of the U.S. and denied the right to fly home. U.S. authorities allowed Gulet Mohamed to fly home after he filed a federal lawsuit, but Mohamed says he remains on the list without justification.