The US accused him of working for Al Jazeera to facilitate "terrorist acts".
|Sami al-Hajj returned to Al Jazeera after recuperating in Sudan following his release
Clive Stafford Smith, a British human rights lawyer who took on al-Hajj's case in 2005, said that in a 2007 review of his case the US alleged that al-Hajj had received terrorist training.
Stafford Smith challenged the allegations, pointing out the review merely stated that "the detainee was trained by Al Jazeera in the use of cameras".
Al-Hajj had previously been accused of filming Osama bin Laden and others with links to al-Qaeda.
His captors also allege that he funded Chechen rebels and that he bought Stinger missiles and shipped them to Chechnya.
But the allegations were baseless. Instead, the US interrogators focused almost exclusively on obtaining intelligence on Al Jazeera.
During his time in prison, Hajj was beaten and interrogated more than 130 times.
Like every other prisoner in Guantanamo, al-Hajj faced regular interrogations and faced a wide range of accusations - all unproven.
Al-Hajj was one of about 20 prisoners who carried out hunger strikes in protest at their imprisonment and treatment.
Up to his release in May 2008, al-Hajj was on hunger strike, which he started on January 7, 2007.
During this period al-Hajj lost weight, developed a kidney infection and was receiving inadequate medical treatment.
Twice a day he was force fed liquid through a tube inserted into one nostril.
The US banned the publication of cartoons drawn by al-Hajj which illustrated his time at Guantanamo.
Drawings entitled Sketches of My Nightmare and Scream for Freedom depicted faceless skeletons in shackles and al-Hajj being force fed in a "Torture Chair'.
Detailed descriptions of the sketches were allowed through the censorship process and Lewis Peake, a British political cartoonist, was able to recreate them.
Calls for release
Meanwhile, Al Jazeera's bureaus held several protests in an attempt to get al-Hajj released.
Alan Johnston, a BBC reporter held for months in Gaza, also appealed for the right of al-Hajj to a fair trial.
Several organisations such as The International Federation of Journalists (IFJ), Reporters Without Borders and Amnesty International urged for al-Hajj's release.
Farouq Abu Issa, a Sudanese member of parliament, also took up the case. In May 2008 the breakthrough came, and el Hajj was released.
In November 2008, he was made Head of Al Jazeera's new Public Liberties and Human Rights Desk, a position he holds today.
Inspired by the suffering he experienced during his time in Guantanamo, the desk aims to give a voice to those experiencing similar abuse.
Al-Hajj was born in Khartoum, Sudan, in 1969. He grew up in central Sudan, the second eldest of six children.
With the help of his uncle, al-Hajj studied English at a university in India before leaving in the early 1990s to take a job at a beverage company in the United Arab Emirates.
He had long been interested in journalism and took up photography in his youth, said his brother Asim Al-Hajj.
Sami al-Hajj is married to Asma Ismailov and is the father of a nine-year old son, who he did not see while he was imprisoned in Guantanamo.