LONDON (Reuters) - Four days after the capture and killing of Muammar Gaddafi, there is little sign of his one missing son Saif al-Islam, last thought to be hiding in a desert area near the town of Bani Walid, which is 150 km (100 miles) southeast of Tripoli.
National Transitional Council (NTC) field commander Abdel Majid Mlegta said on Sunday that fighters were deploying around a place where they believed Saif was hiding after he escaped the siege of his father's hometown of Sirte on Thursday.
Mlegta said Gaddafi's former security chief Abdullah al-Senussi, now in Niger, had contacted Saif to try to help him flee to the Sahelian country "but our brigades are encircling this area south of Bani Walid".
Saif al-Islam Gaddafi is the most enigmatic of Muammar Gaddafi's children, apparently turning within weeks from philanthropist and liberal reformer into a fighter ready to die on his home soil rather than surrender.
Gaddafi junior, whose name means "Sword of Islam", is also the most elusive of the late Libyan leader's eight offspring, wanted on war crimes charges but evading a manhunt for months to remain the only leading family member still at large.
Educated at the London School of Economics and a fluent English speaker, he was once seen by many governments as the acceptable, Western-friendly face of Libya, and a possible heir apparent.
But when a rebellion broke out in February against Muammar Gaddafi's long rule, he immediately chose family and clan loyalties over his many friendships in the West.
"We fight here in Libya; we die here in Libya," he told Reuters Television in an interview early in the rebellion.
Three of Gaddafi's sons have indeed died on their home soil during the civil war, but not Saif.
A senior NTC official said on Friday Saif was fleeing south from the last Gaddafi stronghold of Sirte towards Libya's border with Niger, where another son has already taken refuge.
Saif al-Islam has long been mercurial and elusive.
As Tripoli fell to rebels in August, the International Criminal Court's prosecutor announced he had been arrested, opening the way for his extradition to the Hague court on the war crimes charges.
However, he popped up shortly afterwards at a Tripoli hotel where foreign journalists were staying to prove he remained a free man.
"I am here to disperse the rumours ...," he said, pumping his fists in the air, smiling, waving and shaking hands with supporters.
The ICC later said it had never received official confirmation of Saif's capture.
Gaddafi's four other surviving children -- three sons and a daughter -- are in exile in neighbouring Algeria and Niger.
However, analysts doubt Saif could lead a serious insurgency against Libya's rulers, saying his influence is much reduced with his dominating and intimidating father now dead.
"The answer really is a big 'no'. Saif rose to prominence by virtue of being his father's son," said Jon Marks, chairman of consultancy Cross Border Information.
"Ironically, his biggest boosters during the 'Saif years' -- when he was prominent, but perhaps never dominant given his father's leading role pulling the strings -- are the very governments and politicians who ended up bombing his regime into oblivion."
Before the rebellion Saif al-Islam sometimes appeared genuinely at odds with Gaddafi senior who ruled for 42 years through fear and violence.
Mainly through his charitable Gaddafi Foundation, Saif pushed for reform, including more media freedom, acknowledgement of past rights abuses and the adoption of a constitution.
He also oversaw a reconciliation with Islamist rebels who launched an insurgency in the 1990s.
But his efforts were stymied by opposition from inside the ruling elite and -- some analysts say -- from members of his own family. Last year the independent newspaper he helped to found was forced to mute its criticism of the authorities and his foundation withdrew from political activities.
One of his projects did succeed. He played a central role in negotiating the lifting of U.S. and European sanctions on Libya in 2004, in return for Tripoli ending its nuclear and chemical weapons programmes.
This led to then British Prime Minister Tony Blair visiting Tripoli to embrace Gaddafi senior, long a pariah in the West.
Saif owned a 10-million-pound ($16-million) home in London but his activities and friendship caused much embarrassment in the West when the rebellion broke out.
The director of the London School of Economics, Howard Davies, resigned over the university's ties to its former student.
The LSE had accepted a 300,000-pound donation from Saif al-Islam's foundation, a decision which Davies said had "backfired". The LSE also investigated the authenticity of Saif al-Islam's PhD thesis, which was awarded in 2008.
(Additional reporting by William Maclean; Edited by Richard Meares)