He is being held in the militia stronghold of Zintan.
But as celebrations continue over the arrest of Saif al-Islam, the question remains: where will Colonel Gaddafi's son face justice?
Libyan authorities are adamant; they want a trial on home soil - a view widely shared in the country.
"I hope he is prosecuted in the Libyan courts so he can have a taste of his own medicine and feel the same as the Libyans he has unjustly imprisoned," said Zintan resident Abu Bakr Mohammed. "Libyan prisons were inhuman. This is what I wish. I hope it will happen."