How Saif al-Islam was captured
Saif al-Islam, the highest profile remaining fugitive of the former Libyan regime, was captured in the wilderness near the south-western oil town of Obari, reports say.
The 39-year-old had been on the run since National Transitional Council (NTC) forces took the capital, Tripoli, in August.
He was caught along with several aides apparently attempting to secure passage to neighbouring Niger, a commander of a Zintan militia told a news conference.
Accounts of how Saif al-Islam was captured suggest local fighters were tipped off about his presence near Obari.
A spokesman for the Sabha local revolutionary council told Libyan TV station al-Ahrar that local guide Yousif Salih al-Mahdi was approached by Saif al-Islam and his entourage to smuggle them into Niger.
The spokesman said the guide instead risked his life and contacted the NTC to tell them of Saif al-Islam's whereabouts.
Wisam Dughaly, a fighter from the brigade which says it seized Gaddafi's son, told Free Libya TV: "We got a tip he had been staying there for the last month.
"They couldn't get away because we had a good plan," he said, adding Saif al-Islam had been using a 4x4 vehicle, Reuters news agency reported.
Ahmed Ammar, one of Saif al-Islam's captors, said his unit of 15 men in three vehicles, acting on the tip-off, had intercepted two cars carrying Saif al-Islam and four others in the desert about 70 km (40 miles) from Obari at about 01:30 (2330 GMT on Friday).
The fighters halted the car and asked the identity of the travellers, Mr Ammar told Reuters.
The man in charge said he was "Abdelsalam" - "servant of peace". But the fighters quickly recognised him as Saif al-Islam and took him without a fight.
The commander of the Zintan militia told the BBC that Saif al-Islam had two Kalashnikovs and a Belgian rifle with him but he had been caught by surprise and did not use them.
He said Saif al-Islam was no doubt aware of his father's fate and showed some fear. He asked the fighters to shoot him dead but they refused, the commander added.
Saif al-Islam then agreed to be taken to Zintan.
'Taken for trial'
Mr Dughaly said Saif al-Islam would be held in Zintan "for safekeeping" until a government is formed and would then be handed over.
"He was not hurt and will be taken safely for trial," he said.
A Reuters journalist aboard the plane which flew the detainee to Zintan said he was wearing traditional robes and had a thick black beard.
His thumb and two fingers were bandaged, an injury he said he had sustained in a Nato air strike a month ago.
Saif al-Islam is a prize for local fighters and his treatment will be the subject of intense scrutiny over coming hours and days, following controversy over the capture and subsequent killing of his father.