Determined to hunt down Muammar Gaddafi, Libya's new rulers say they have dedicated a special unit of fighters to track the elusive former leader, listening in on his aides' phone calls, poring over satellite images and interviewing witnesses.
Although leads come mostly from on-the-ground tips, help is also coming from France and other Western countries, according to a French intelligence official.
Satellite-based transmission intercepts of suspicious phone calls try to pinpoint where Gaddafi might be.
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Small CIA teams are also assisting in the manhunt, according to former US officials.
Gaddafi, who hasn't been seen in public for months, went underground after anti-regime fighters swept into Tripoli on August 21.
Capturing the ousted ruler would allow the former rebels to seal their grip on the country and shut the door on the possibility of Gaddafi's inspiring an insurgency against the new leaders.
After more than four decades under his authoritarian rule, Libyans are haunted by the question of Gaddafi's whereabouts, and the country has been awash with rumours that have put him everywhere from deep in a bunker under Tripoli to safe in exile in neighbouring Niger or Algeria.
Gaddafi himself dismissed talk of his flight, saying in an audio broadcast on Thursday that he's still in Libya, and exhorting followers to keep fighting.
One anti-Gaddafi fighter said revolutionary forces stormed a villa on Tripoli's outskirts last week acting on a tip.
The fighter, who took part in the operation, said they believe Gaddafi was at the villa and escaped less than an hour before the raid through a secret tunnel. Computers were on and cups of tea were still warm, he said, indicating the occupants had just fled.
Two chefs working at the villa were detained and documents recovered, the fighter said.
Officials say the most reliable reports, culled from witnesses and informants, put the fugitive leader in or near one of three remaining strongholds of loyalist support - his hometown of Sirte on the Mediterranean coast, the city of Bani Walid southeast of Tripoli, or the city of Sabha deep in the southern desert.
Anis Sharif, a spokesman for the Tripoli military council, said the former rebels have a unit of more than 200 "special forces" leading the manhunt in collaboration with the operations room in the capital.
He claimed they have located Gaddafi - he would not say where - and that his capture is "just a matter of time."
"We are tracking his movements," Sharif said in an interview. "He's moving in a small convoy of cars trying to avoid any attention from NATO or the rebels, but successfully we have located a 60 square kilometre area where he's moving. He's trying not to stay in the same place for more than two or three hours."
The operation is drawing on technology, tips from people on the ground and witnesses to try to pinpoint Gaddafi's location.
"We are tracking the phone calls for his aide, we know he's trying not to use the phone himself," Sharif said. "We are using satellite photos as well."
Three former US officials have said the former rebels are receiving help in the search from small CIA teams, including former US special operators on contract to the intelligence agency, as well as a small number of advisers from British and French special operations teams.
CIA officers on the ground will touch base with sources who have kept them informed throughout the battle to oust Gaddafi. But the agency does not yet have officers in sufficient numbers or the human intelligence network built on the ground to help the rebels conduct an effective manhunt.
