But Algeria's human rights record is frequently criticised and anyone suspected of having links to terrorism - even unproven allegations like those against Naji - can expect to attract unwelcome attention from the country's security services.
Naji also repeatedly expressed fears that if returned to Algeria, he would be targeted by violent groups who would kill him if he refused to join their battle against the country's government.
Lawyers said on Monday that the Obama administration could have acted illegally by sending him back to Algeria.
"Our government repatriated him against his will and despite credible fears of future persecution, in violation of the UN Convention Against Torture and other international law," a statement issued by the Center for Constitutional Rights said.
The organisation said it supported attempts to close Guantanamo Bay, but warned that detainees should not be forced to return to countries where they could be persecuted.
"The solution to Guantanamo Bay does not rest on forcing detainees to return to countries where they fear torture and persecution," the statement said.
"It is not only illegal, but also bad policy. It is another unnecessary stain on our country’s human rights record, and certain to upset our friends and allies around the world."
The US government obtained a key court decision paving the way for returns to Algeria earlier this month, when a ruling that blocked the return of Algerians being held in Guantanamo was overturned in an appeals court.
There are a further five Algerians being held at the prison who have been cleared for released but do not want to be returned to Algeria.
The Algerian government is accused of employing a range of human rights abuses, including torture, to suppress an violent Islamist uprising that has claimed thousands of lives since 2002.
The most recent US state department human rights report on Algeria said that "local human rights lawyers maintained that torture continued to occur in detention facilities, most often against those arrested on 'security grounds'".
The US has in the past refused to repatriate Guantanamo prisoners to several countries, including China, Libya and Syria, because of concerns they could be mistreated when they arrive.
There are 178 prisoners still being held at Guantanamo Bay. Barack Obama, the US president, had pledged to close the prison within a year of taking office but missed the deadline.
Experts now say that Guantanamo is unlikely to close before the next presidential election.