FILE - In this Jan. 16, 2009 photo released by the International Committee of the Red Cross via his lawyer Andy Savage, Ali al-Marri is seen at the Charleston Naval Brig in Charleston, S.C. A two-day sentencing begins Wednesday, Oct. 28, 2009, at federal court in Peoria, Ill., for al-Marri, a former Bradley University student and a married father of five from Qatar who pleaded guilty to one count of conspiring to provide material support or resources to a foreign terrorist organization. He faces up to 15 years in prison. (AP Photo/ICRC via Andy Savage, File)

FILE - In this Jan. 16, 2009 photo released by the International Committee of the Red Cross via his lawyer Andy Savage, Ali al-Marri is seen at the Charleston Naval Brig in Charleston, S.C. A two-day sentencing begins Wednesday, Oct. 28, 2009, at federal court in Peoria, Ill., for al-Marri, a former Bradley University student and a married father of five from Qatar who pleaded guilty to one count of conspiring to provide material support or resources to a foreign terrorist organization. He faces up to 15 years in prison. (AP Photo/ICRC via Andy Savage, File)

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Defense attorneys for an al-Qaida sleeper agent plan to argue at his sentencing this week that his five years spent locked up without charge was enough punishment and he should be immediately released.

Former Bradley University student Ali al-Marri, a 44-year-old native of Qatar, pleaded guilty in May to one count of conspiring to provide material support or resources to a foreign terrorist organization. He will be sentenced this week in a federal court in Peoria, Ill.

Prosecutors have recommended the maximum 15 years behind bars, and the judge's decision could have far-reaching effects. The United States still holds more than 200 people without charge at Guantanamo Bay. If convicted, those detainees also could argue that their time in custody should be considered at sentencing.

Prosecutors have declined to comment before the sentencing. But in court documents, they wrote that al-Marri "was fully aware of the nature of al Qaeda's violent philosophy against the United States and their ability to inflict mass casualties. He agreed to the mission knowing that it would be in furtherance of that agenda."

Al-Marri's attorneys say the judge who will preside over Wednesday and Thursday's sentencing hearing should consider the years al-Marri spent locked up without charge, much of it in a U.S. Navy brig in South Carolina. Those years and cruel treatment – including sensory deprivation, lengthy interrogations and threats to harm his family – amount to a sentence "beyond what our nation stands for and tolerates as a matter of respect for the law," they said in court documents.

"We're arguing that, that warrants a lower sentence," attorney Lawrence Lustberg said in an interview Monday. "The best possible outcome would be that the court would conclude that no additional term is necessary."

Judge Michael Mihm can't directly credit al-Marri for time spent locked up before he was charged, but he can give him a light sentence, Lustberg said, even as little as the months he has spent behind bars since he was charged.

Al-Marri has admitted that he trained in al-Qaida camps and stayed in al-Qaida safe houses in Pakistan between 1998 and 2001, learning how to handle weapons and communicate by phone and e-mail using code.

He also acknowledged having regular contact with Khalid Sheikh Mohammed, the man who the government said was the mastermind behind the Sept. 11 attacks, and with Mustafa Ahmad al-Hawsawi, who allegedly helped the Sept. 11 hijackers with money and Western-style clothing.

In 2003, President Bush declared al-Marri an enemy combatant, one of three held on U.S. soil since the 2001 attacks.

After the U.S. Supreme Court agreed in December 2008 to consider al-Marri's challenge of his enemy combatant status, President Barack Obama ordered him surrendered to civilian authorities in Peoria, where Bradley University is located and where al-Marri was indicted.

University of Illinois law professor Steven Beckett believes that Lustberg has a tough case to make. He said judges in Illinois' Central District usually follow federal sentencing guidelines and whatever decision Mihm makes is likely to be appealed because of the affect it could have on future cases.

Stephen Ellmann, a dean at the New York Law School and critic of military trials held at Guantanamo, said al-Marri's admission that he was an al-Qaida member gives prosecutors a basis for seeking the maximum sentence.

"The underlying rationale for military detention remains, even if military detention wasn't appropriate or constitutional, that he might return to the battlefield or the terrorist struggle," Ellmann wrote in an e-mail. "And that's a reason to seek the maximum possible sentence."

But one of al-Marri's brothers said this week that al-Marri's relatives – who live in Saudi Arabia – are optimistic that they'll see him soon.

"What he has been in for is more than enough," Mohammed al-Marri said in a telephone interview. "They are waiting for this moment, for him to be released."