Aides who were captured at Bani Walid said Saif al-Islam's convoy had been hit by a NATO air strike in a place nearby called Wadi Zamzam - "Holy Water River." Since then, there had been speculation that nomadic tribesmen once lionized by his father might have been working to spirit him across Libya's southern borders - perhaps, like his surviving brothers, sister and mother, into Niger or Algeria.
He did not get that far. Obari is a good 200 miles from either. But his captors believe he was headed for Niger, once a beneficiary of Muammar Gaddafi's oil-fueled largesse, which has granted asylum to Saif al-Islam's brother Saadi.
"WHO ARE YOU?"
Ammar said his unit, scouring the desert for weeks, received a tip-off that a small group of Gaddafi loyalists - they did not know who - would be heading on a certain route toward Obari. Lying in wait, they spotted two all-terrain vehicles grinding through the darkness.
"We fired in the air and into the ground in front of them," Ammar said. The small convoy pulled up, perhaps hoping to brazen it out.
"Who are you?" Adeljwani Ali Ahmed, the leader of the squad, demanded to know of the man he took to be the main passenger in the group.
"Abdelsalam," came the reply.
It's a common enough name, though it means "servant of peace" in Arabic; Saif al-Islam's real name means "Sword of Islam."
Ahmed, sizing the man up, took Ammar aside and whispered: "I think that's Saif."
Turning back to the car, a Toyota Land cruiser of a type favored on these rugged desert tracks, Ammar said: "I know who you are. I know you."
CASH AND KALASHNIKOVS
The game was up. The militiamen retrieved several Kalashnikov rifles, a hand grenade and, one of the Zintani fighters said, some $4,000 in cash from the vehicles.
It was a tiny haul from a man whose father commanded one of the best-equipped armies in Africa and who is suspected by many of holding the keys - in his head - to billions stolen from the Libyan state and stashed in secret bank accounts abroad.
"He didn't say anything," Ammar said. "He was very scared and then eventually he asked where we are from, and we said we are Libyans. He asked from which city and we said Zintan."
Zintan sits far from the spot of Gaddafi's capture in the Western, or Nafusa, Mountains, just a couple of hours drive south of the capital. The people of Zintan put together an effective militia in the uprising, and they are seeking to parlay their military prowess into political clout as new leaders in Tripoli try to form a government.
At Obari, a fly-speck of a place dominated by the oil operations of a Spanish company, Zintan fighters have extended their writ since the war deep into traditionally pro-Gaddafi country peopled by Tuaregs, nomadic tribes who recognize no borders.
The Zintanis are also a force in the capital. Saturday morning, the Antonov flew to Obari from Tripoli, bearing the new tricolor flag of "Free Libya" - and piloted by a former air force colonel turned Zintan rebel. Just a few minutes after it landed, the purpose of the flight became clear.
FLIGHT TO CAPTIVITY
Five prisoners, escorted by about 10 fighters in an array of desert camouflage, piled aboard, ranging themselves on benches along the sides of the spartan hold of the Antonov An-32, which is designed to carry four dozen paratroopers.
Two of the men were handcuffed together. A third had his arms cuffed in front of him. A dozen or so bulky black bags were carried in, and some thin mattresses - the scant belongings of the prisoners, their captors said.
All wore casual, modern dress - with the exception of Saif al-Islam.