An al-Qaida sleeper agent who admitted having contact with the alleged mastermind behind the Sept. 11 terrorist attacks was sentenced to more than eight years in prison Thursday, AP reported.

U.S. District Judge Michael Mihm could have sentenced Ali al-Marri to as much as 15 years. But he handed down the lighter sentence of eight years and four months in consideration of what defense attorneys' called harsh treatment during the almost six years al-Marri was held without charges in a U.S. Navy brig.

The judge's decision could have far-reaching consequences because the United States still holds more than 200 people without charge at Guantanamo Bay. If convicted, those detainees also could argue their time in custody should be considered at sentencing.

Al-Marri, a 44-year-old Qatar native, pleaded guilty in May to conspiring to provide material support or resources to a foreign terrorist organization.

He wept through his 10-minute testimony Thursday, telling Mihm he was sorry he ever helped the terrorist organization and glad his actions never led to any harm.

Mihm told al-Marri he didn't believe he'd renounced al-Qaida and thought he was likely to attack the U.S. if given the chance. But he also said al-Marri deserved credit for the time he'd spent in isolation in the Navy brig in South Carolina. While Mihm couldn't directly credit al-Marri for that time, he had the option of giving him a lighter sentence.

Al-Marri quietly thanked Allah in Arabic when Mihm delivered the sentence.

Al-Marri's relatives heard the news at about 11:20 p.m. in Saudi Arabia. They had been hoping al-Marri would receive probation, and his brother said previously he hoped to see al-Marri soon.

"I don't know what to say," Naji al-Marri, al-Marri's brother, said by telephone. "Did they count the years he spent in prison?"

During the two-day sentencing hearing, defense attorneys showed videos and presented testimony to show al-Marri had endured cruel treatment - including sensory deprivation, lengthy interrogations and threats to harm his family - during almost six years in the Navy brig. In court documents, they argued that amounted to a sentence "beyond what our nation stands for and tolerates as a matter of respect for the law."

Prosecutors had argued for the maximum sentence, presenting testimony to try to prove al-Marri would still try to inflict harm on the U.S. if he had a chance. They have 10 days to appeal the sentence but said no decision on that has been made yet.

Al-Marri admitted 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.

He was arrested in December 2001 while a graduate student at Bradley University in central Illinois. 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 he was indicted.

Prosecutors said al-Marri deserved the maximum sentence, writing in court documents he "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."

During al-Marri's sentencing hearing, an Air Force psychologist testified she believed al-Marri would attack the U.S. if given a chance.

Maj. Deborah Sirratt said she based her conclusion on hours of interaction with al-Marri while she was in charge of medical care in the U.S. Naval Consolidated Brig in Charleston, S.C. She said he believed infidels - unbelievers - should be killed, talked about his beliefs as an al-Qaida member and thought "Americans should get out of the Middle East."