The prosecutor for the International Criminal Court (ICC) said on Sunday he has "substantial evidence" that Saif al-Islam Qadhafi, now on the run, had helped hire mercenaries to attack Libyan civilians protesting against his father's rule.
Saif al-Islam may be heading for Niger, which risks upsetting its own pro-Qadhafi Tuareg nomads if it hands him over to the ICC in line with its treaty obligations, as it has promised to do if the wanted man shows up on its territory.
"We have a witness who explained how Saif was involved with the planning of the attacks against civilians, including in particular the hiring of core mercenaries from different countries and the transport of them, and also the financial aspects he was covering," ICC prosecutor Luis Moreno-Ocampo told Reuters during a visit to Beijing.
Saif al-Islam, 39, is desperately seeking to avoid the fate of his father, Muammar Qadhafi, who was beaten, abused and shot after forces of Libya's National Transitional Council (NTC) captured him on October 20 after the fall of his home town Sirte.
The NTC may try Saif al-Islam itself, but the fugitive Libyan has been in indirect contact with the ICC over a possible surrender, though he may also harbour hopes that mercenaries can spirit him to a friendly African country.
Neighbouring Niger has vowed to honour its ICC commitments, but knows that handing over Saif al-Islam could spark unrest in Saharan areas where his father, feted by many desert-dwellers as a hero, nurtured past Tuareg revolts against the capital.
A senior member of Niger's coalition government told Reuters Saif al-Islam's whereabouts remained unknown, but that surrender was his best option. Niger would cooperate with the ICC to ensure he was handed over as safely as possible.
"It's perhaps best that he goes of his own accord rather than to be hunted and caught by Libyans who will end up lynching him as they did to his father," said Habi Mahamadou Salissou, vice-president of the Nigerien Democratic Movement.
The former foreign minister said he was convinced that any transfer of Saif al-Islam would not spark a new Tuareg revolt in the West African nation, pointing to recent government efforts to integrate Tuareg officials into positions of power.
But he acknowledged the imprint the former Libyan leader had left on Niger. "Qadhafi backed virtually all the rebellions in Niger and then managed to find a solution to them."
Moreno-Campo said the ICC had witnesses to testify against Saif al-Islam, whom he said he had met a few years ago - when Saif had backed ICC efforts to arrest Sudanese President Omar al-Bashir over alleged genocide and other crimes in Darfur.
"So we have substantial evidence to prove the case, but of course Saif is still (presumed) innocent, and (will) have to go to court and the judge will decide," he said. Moreno-Ocampo said he would brief the UN Security Council on Wednesday about the court's work in Libya.
The Hague-based court has warned Saif al-Islam that it could order a mid-air interception if he tried to flee by plane from his unidentified Sahara desert hideout for a safe haven.