A few weeks after the NATO bombing campaign began, Abdullah and four of his fellow Tuareg agreed to desert. "We decided that Qaddafi was a little bit crazy and didn't know what he was doing." They told the Tuareg officer in charge of their platoon they needed a rest, and he convinced the Arab commanding officer to approve a pass for the men to visit their families. "He knew we weren't coming back," Abdullah said of the Tuareg officer.

They took a bus to the south. Some of the men disassembled their Kalashnikovs and took them with them. Once in the southern Libyan town of Awbari, Abdullah burned his uniform and all his identity papers and, with his wife and four children, slipped out of the city to join other Tuareg refugees heading for the Algerian border. Able to bring only their clothes and a few household items, they left everything else.

I asked if he regretted his decision to go to Libya. He hesitated before answering. "The Tuareg say, 'It is easy to climb into a well and very hard to get out.'"

I checked his story with other Tuareg in Timbuktu, who corroborated parts of it based on what they had heard from other fighters, but many details are unverifiable. An official -- not a Tuareg -- in the mayor's office confirmed that some men have arrived from fighting in Libya, though he doesn't know how many. "I don't count them," he said. "No one wants to talk about that."

A few days later, in Mali's capital Bamako, I met a Tuareg officer in the Mali army. He was rawboned with thick, leathery hands and heavy lines creasing his forehead and around his eyes. Years of desert fighting have made him look much older than his 42 years. As a young man, he said, he was lured to Libya in the 1980s by radio broadcasts of Qaddafi calling young Tuareg to join his revolution. "I admired the way he wasn't afraid to stand up to the West, to anybody," he said.

But after being sent to the Libya-Chad war and seeing how Libya's Arabs used the Tuareg to do all the "difficult fighting," he lost his ardor for Qaddafi. He left Libya and joined the Tuareg rebels who were fighting the Mali government in the early 1990s.

I asked about the implications of mercenaries such as Abdullah coming back home to find few economic opportunities. "It is not good," he said, listing the security threats Mali faces, including a resilient, well-financed branch of al-Qaeda, which in recent years has kidnapped dozens of foreigners, effectively wrecking the country's tourism industry, and a fragile peace in the restive Tuareg region. "It is like dragging a dead tree on top of two small fires," he said. "Soon we may have one big fire."

"If Qaddafi goes, it's going to be very bad for Mali." He estimated that roughly 10,000 Tuareg remained in the Libyan army, most of them from Mali. "If Qaddafi is killed or loses power, they will all have to leave. The Arabs won't let them stay," he said. "I know many guys there. When they come here, they will fight. I have no doubt. I know them. The revolution is not over."

Before I left Timbuktu, I encountered a group of boys huddled over their cell phones. Clad in knockoff European soccer jerseys, they periodically whooped with laughter as they passed around a song using Bluetooth.

I asked what it was, and the skinniest boy, draped in an oversize Barcelona jersey, played it for me: A man shouted defiantly in Arabic followed by automatic gunfire, a house beat, and rap lyrics. "It is Qaddafi," said the boy. "He is calling the people to fight." "Zenga-zenga," added the tallest boy in a striped Inter Milan shirt. They played it again and laughed. "What does zenga-zenga mean?" I asked. "Corner by corner," said Barcelona, "he is telling people he will fight village by village, house by house, room by room, corner by corner -- zenga-zenga."

Do you like Qaddafi? I asked them. They all nod. "He is a warrior, like the Tuareg," said Barcelona. The others click their tongues in agreement. They disappeared into the darkening alleyways, heading in separate directions. I could hear them each playing the tune, spreading it through the city.

Reuters reported on Saturday that Ibrahim ag Bahanga, the Mali rebel leader turned mercenary, was killed near the Mali-Niger border. Though the circumstances remain unclear, one Mali military official indicated that fellow Tuareg shot him after they had smuggled weapons into the country from Libya. Meanwhile, on Sunday Agence France Press reported large numbers of Tuareg fighters returning to northern Niger with luxury cars and furniture.

This story was reported with support from the Pulitzer Center for Crisis Reporting and as part of a report for National Geographic on the Tuareg.