Photographs that had been posted on a media site on internet showed the former businessman and soccer player, who is 39, in a uniform from the prison having his hair cut off as he stood before the Libyan judiciary emblem.
He has been accused of being the instigator in the recent unrest in southern Libya in which dozens have been killed due to ethnic fighting.
Some people in Tripoli fired weapons into the air celebrating the news of Gaddafi’s extradition.
Like the other surviving Gaddafi clan members, Saadi had been in Niger seeking asylum. Unlike Saif al-Islam, his elder brother who was taken into custody just days after the collapse in 2011 of his father’s regime of four decades, Saadi is not wanted for any war crimes by international authorities.
Saadi is described often times as a playboy more interested in his hedonistic pleasures than in the pursuit of power.
The government of Libya accused him of trying to repress the revolution in 2011 and for disturbing the stability and security including in the events that have taken place in the southern part of the country.
He could also face charges of corruption from business dealings for allegations he set up reprisals against rivals during his tenure as the head of the football federation in Libya.
It is reported that Gaddafi went through a medical exam and that he would be interrogated soon. A statement issued by the government vowed the defendant would be treated in accordance fairly and by international standards.
However many question the fairness and efficacy of the justice system in Libya.
A report in February by the Human Rights Watch was critical of the lack of due process for the former officials of the government. Defendants have alleged they have been unable to meet with lawyers or could not review adequately the evidence in their cases.