Saadi was presented before the court for the first time since his extradition from Niger in March. He was suspected of murdering the Libyan football player Bashir Riani, Xinhua quoted the official LANA news agency as saying in a report.
Saadi, the third son of Muammar Gaddafi, once played football for clubs both in his home country and in Italy's Perugia.
The attorney general's office is expected to charge Saadi for other offences as well, including suppression of civilians during the 2011 turmoil, and support for insurgents in southern Libya aiming to overthrow the present government, local media reported.
Former officials of Gaddafi's government, including former intelligent chief Abdullah Senussi and former prime minister Baghdadi Mahmudi, also appeared before the court, facing charges of systematic rape, inciting violence and sabotaging national unity during the war that toppled the former administration.