Saif al-Islam Gaddafi is expected to try to surrender to the International Criminal Court or seek refuge in a friendly African country as he races to escape his father's fate.
The Hague-based ICC said on Friday the 39-year-old had been in touch. It urged him to turn himself in, warning it could order a mid-air interception if he and his mercenary guards tried to flee by plane from his desert hideout for a safe haven.
The ICC's comments offered some corroboration of reports from Tripoli's new National Transitional Council (NTC) leaders and African neighbours that he has taken refuge with Tuareg nomads in the borderlands between Libya and Niger.
Through intermediaries, we have informal contact with Saif, ICC Prosecutor Luis Moreno-Ocampo said in a statement.
We have learnt through informal channels that there is a group of mercenaries who are offering to move Saif to an African (state) not party to ... the ICC. The Office of the Prosecutor is also exploring the possibility to intercept any plane within the air space of a state party in order to make an arrest.
In Beijing on Saturday, Moreno-Ocampo said Saif al-Islam was saying he would prove he was innocent of alleged crimes against humanity.
NTC officials told Reuters earlier this week that monitoring of satellite calls and other intelligence indicated Saif al-Islam was considering turning himself in to the ICC, and trying to arrange an aircraft to get him there and out of reach of NTC fighters, in whose hands Muammar Gaddafi was killed a week ago.
However, surrender is only one option. The Gaddafis made friends with desert tribes in Niger, Mali and other poor former French colonies in West Africa, as well as farther afield in countries like Zimbabwe and Sudan, some of them also recipients of largesse during the 42-year rule of Muammar Gaddafi, a self-styled African king of kings.
France, a key backer of February's revolt, reminded Africans of obligations to hand over the surviving ICC indictees - former intelligence chief Abdullah al-Senussi and Saif al-Islam.
We don't care whether he goes on foot, by plane, by boat, by car or on a camel, the only thing that matters is that he belongs in the ICC, said Foreign Ministry spokesman Bernard Valero. We don't have many details, but the sooner the better.
Niger, Mali, Chad and Burkina Faso, a swathe of arid states to the south of Libya, are all signatories to the treaty that set up the ICC, established to give a permanent international tribunal for crimes against humanity after ad hoc bodies set up for Rwanda, the former Yugoslavia and Sierra Leone.
If we reach agreement, logistical measures for his transfer will be taken, ICC spokesman Fadi El Abdallah said. There are different scenarios, depending on what country he is in.
Without its own police force, the ICC depends on cooperation from member states, which do not include world powers the United States, Russia and China.
Algeria, which took in Saif al-Islam's mother, sister, brother Hannibal and half-brother Mohammed, is not a signatory. Nor are Sudan or Robert Mugabe's Zimbabwe.
As well as enjoying protection from Tuareg allies who traditionally provided close security for the Gaddafis, Saif al-Islam may still be in the company of mercenaries from elsewhere in Africa, including possibly South Africa, NTC officials say.
A South African newspaper, in an unconfirmed report, said South African mercenaries were working to fly him out.
A bodyguard who saw Saif al-Islam as he fled last week from one of the Gaddafi clan's last bastions near the capital told Reuters that he seemed nervous and confused. He escaped even though his motorcade was hit by a NATO air strike as it left Bani Walid on October 19, the day before his father died in Sirte.
Three of Saif al-Islam's brothers were killed in the war. Another, Saadi, has found refuge in Niger.
The arrest or surrender of Saif al-Islam would bring a new prominence for the nine-year-old ICC, whose highest profile suspect to date is Sudanese President Omar al-Bashir, who remains defiantly in office, defended by many fellow Africans.
Following the killing of Muammar Gaddafi, most probably at the hands of fighters who filmed themselves battering and abusing him, Western allies of Libya's new leaders urged them to impose respect for human rights.
NTC leaders would like to run their own trials, but acknowledge that their writ barely runs in the deep south.
Their NATO allies, now winding up a mission that backed the revolt, have expressed little enthusiasm for hunting a few individuals across a vast tract of empty continent -- though French troops based in West Africa might be best placed to step in with transport if Saif al-Islam did choose to surrender.
The ICC's Moreno-Ocampo said in his statement: If he surrenders to the ICC, he has the right to be heard in court, he is innocent until proven guilty. The judges will decide.
If the judges decide that Saif is innocent, or has served his sentence, he can request the judges to send him to a different country as long as that country accepts him.
Saif al-Islam was once seen as a liberal reformer, architect of a rapprochement with Western states on whom his father waged proxy guerrilla wars for decades. But he responded with belligerent rhetoric after the revolt erupted in Libya.
The ICC accuses him of hiring mercenaries to carry out a plan, worked out with his father and Senussi, to kill unarmed protesters inspired by Arab Spring uprisings elsewhere.
Niger's government in the capital Niamey has vowed to meet its ICC commitments. But 750 km (400 miles) north in a region where cross-border allegiances among Tuareg nomads often outweigh national ties, the picture looks different.
For now, some of the tens of thousands of people who eke out a living in the deepest Sahara, an expanse roamed by smugglers and nomadic herders, say there would be a welcome for the younger Gaddafi.
We are ready to hide him wherever needed, said Mouddour Barka, a resident of Agadez in northern Niger. We are telling the international community to stay out of this business and our own authorities not to hand him over -- otherwise we are ready to go out on to the streets and they will have us to deal with.
Mohamed Anako, president of Agadez region, the size of France, said: I am ready to welcome him in. For me his case is quite simply a humanitarian one.
Libya and Niger are brother countries and cousins ... so we will welcome him in.
(Additional reporting by Sara Webb and Aaron Gray-Block in Amsterdam, Samia Nakhoul in London, Mark John in Dakar, Ibrahim Diallo in Agadez and Barry Malone in Tripoli; Editing by Myra MacDonald and Ralph Gowling)