Libya's interim authorities have captured the last totem of the Gaddafi regime, seizing former intelligence chief Abdullah al-Senussi in the southern desert near to where Saif al-Islam Gaddafi was apprehended two days earlier.

Militia units surrounded a house where Senussi was holed up, near the town of Birak. The arrest means that all leading figures from the Gaddafi regime have now either been killed, captured or driven into exile. Senussi was the henchman of the Gaddafi regime, "the executioner", according to Luis Moreno Ocampo, prosecutor at the international criminal court.

Both Senussi and Saif al-Islam have been indicted by the ICC on war crimes charges for their role in the bloody suppression of anti-government protests this year. But after they trumpeted his capture, Libyan officials said Saif al-Islam would not be handed over to the Hague court, but tried at home. The charges against him could carry a death penalty.

The National Transition Council's spokesman, Mahmoud Shamman, said Libya's interim government would inform the ICC of its decision next week.

Ocampo, is expected to visit Tripoli on Monday. He will urge Libya's rulers that any trial of Saif al-Islam should be carried out in full accordance with international norms.

Speaking to the Associated Press, Shamman said it was wholly appropriate that Gaddafi's son and one-time heir receives justice within his country since it was here he "committed crimes against the Libyan people".

But it remains unclear whether Saif al-Islam's captors based in the western mountains would agree to hand over Gaddafi's favourite son to the authorities in Tripoli. Libya's prime minister, Abdurrahim al-Keib, is about to announce a new cabinet.

Saif al-Islam is the ultimate bargaining chip for Zintan, keen to secure maximum influence in the new government above other regional claimants.

"We can try him, it will not take too long, we don't need any new laws," said Omran Eturki, leader of Zintan council, referring to questions over Libya's current legal limbo. "They are Zintanis who captured him so they will have to have him here.

"The judicial authorities can appoint the judges and the lawyers, but the trial must be here. As long as there is justice, that is it."

He said Saif al-Islam would get a fair trial. "There is no point to make a revolution for justice, and then you become the same killers. All the people of Zintan want to see him have a proper trial. We don't like to harm him. If we wanted to kill him we could kill him. We captured him so I think we have the right to try him."

Saif al-Islam was apprehended in the desert near Obari, a small town that straddles roads leading to Algeria and Niger.

The man who led the fighters that captured him said the late dictator's son tried to escape arrest by pretending to be a camel herder.

"When we caught him, he said, 'My name is Abdul Salem, a camel keeper,'" said commander Ahmed Amur on Sunday. "It was crazy."

"We knew it was a VIP target, we did not know who," said Amur. After stopping the two cars containing Saif al-Islam and four others, Amur said Saif al-Islam threw himself face down and began rubbing dirt on his face. "He wanted to disguise himself. His face was covered [with dirt], I knew who he was," said Amur. "Then he said to us, 'Shoot.' When the rebels refused to shoot, and identified themselves, Saif al-Islam told them: 'OK, shoot me, or take me to Zintan.'

"We don't kill or harm a captured man, we are Islam," said Amur, still clad in the green combat jacket he wore when making the arrest. "We have taken him here to Zintan. After that, our government is responsible."

A Ukrainian doctor who treated Saif al-Islam said he would need to have several fingers amputated to prevent infection spreading. Dr Andrew Morokovsky, from Krivoi Rog, has been working in Zintan hospital for eight years and stayed to tend wounded fighters when war broke out in Libya in February.

"It's an old wound, the wound was septic. He [Saif al-Islam] told me it was from Nato bombing. The fingers have rupture, I don't know, maybe bombing, yes."

He said he would perform an operation to cut the fingers lower down the bone. "There has to be reamputation, and close the skin," he said.

Morokovsky said Saif al-Islam seemed calm when they met, and was thin but otherwise healthy. "He was very nice, he's not scared." The doctor said the fighters had asked him to perform the operation in Zintan, but that it was not clear if they wanted it done in the house where he is captive or the town's single hospital. Morokovsky said he preferred the hospital. "It is better for me and for him to do it here [the hospital]. It has more facilities."

Senussi built up a reputation as the enforcer of Gaddafi's will when he was the chief of security during a deadly purge of regime opponents in the early 1980s. Many Libyans also hold Senussi responsible for the 1996 killing of around 1,200 inmates at Abu Salim prison in Tripoli.