The revolution is long over in Libya, but gunfire still crackles in the night, echoing down empty streets and alleys.
Swaggering men in Che Guevara-style berets patrol the outskirts of once-besieged Misurata with antiaircraft guns affixed to the back of their pickup trucks, stalking those they believe are responsible for their city's misery.
A militia based in mountainous Zintan refuses to hand over Moammar Kadafi's son and once heir-apparent, Seif Islam Kadafi, and encirclesTripoli's airport, holding both as bargaining chips to extract concessions and avoid being marginalized in the country's emerging political order.
Six months after Kadafi was ousted, well-armed militias made up of former rebels present an increasing threat to Libya's precarious stability.
Amnesty International describes the militias as "largely out of control." Others view them as a temporary scourge in a country torn by retribution and tribal rivalries.
Traveling in reckless caravans across deserts and through cities, the militias defy easy categorization and represent a direct challenge to the overwhelmed Transitional National Council.
The distrusted and opaque interim authority lacks the muscle to rein in the armed groups numbering in the hundreds, which have become a law unto themselves.
"The core issue is legitimacy," said William Lawrence, the North Africa director of the International Crisis Group. The transitional council "is not representative of the Libyan people."
The secrecy surrounding the council's decision-making and membership has provided little incentive for Libya's militias, still traumatized by the uprising and fearing political marginalization, to disarm.
"When we have security, a new president and government, we will put our weapons away," said Ayman Kikly, from a Tripoli militia.
Rising inter-tribal violence has left scores dead. About 100 people were reported killed last month when rival tribes battled with machine guns and rocket-propelled grenades in the remote southern town of Kufra, probably for control of lucrative arms-smuggling and human-trafficking routes in the vast empty spaces near the Chadian and Sudanese borders.
The surge in violence has raised fear of spreading chaos as weapons continue to flow out of the country to Egypt, Tunisia, Chad and Algeria.
The militias' actions and "the refusal of many to disarm or join the regular forces are threatening to destabilize Libya," says a recent report by Amnesty International. The report says armed gangs "hinder the much-needed building of accountable state institutions based on the rule of law, and jeopardize the hopes of millions of people who took to the streets a year ago to demand freedom, justice and respect for human rights and dignity."
A spate of torture, arbitrary arrests, wanton destruction of property and summary execution has beset the country, engendering an environment of impunity while ensuring that Libya's people remain trapped within the violent logic of last year's insurgency.
"The blanket impunity afforded to militias is sending the message that such abuses are tolerated and is contributing to making such practices accepted practice," Donatella Rovera, a senior crisis response advisor at Amnesty, said in a statement.
In one recent attack that spotlighted the chaotic violence, Khaled Nouri and five other militiamen guarding an abandoned naval compound on the outskirts of Tripoli came under fire from a convoy of 20 pickup trucks carrying another militia, believed to be from Misurata.
They scattered as more gunshots rang out. By the assault's end, a 63-year-old woman had been shot in the head and two boys, their bodies riddled with bullets, were lying face down on a nearby beach. Four other bodies lay strewn in the compound, where 2,600 Tawurghans, African descendants of black slaves suspected of collaborating with the Kadafi regime, had taken shelter after their town had been burned and looted.
"They came for one thing," said Nouri: "To kill the Tawurghans."
"I am afraid they will come back after dark," said Abdul Raouf, who guards the compound by night, while nervously clutching his rifle. "We are six people with Kalashnikovs, how can we stop them?"
Moves to integrate militia members into the armed forces have met some success. Yet 100 militias recently formed a collective, establishing a rival power center that challenges the transitional council's authority.
Many people prefer to place their faith in local military councils and the militias. Both have legitimacy and superior knowledge of the local context, and often residents feel the militias are best-equipped to provide security.
"Everything is perfect," said Ali Mohammed, a taxi driver who shuttles passengers from Zintan to Tripoli and from Misurata to Benghazi. "The militias have made the country safe. You can walk down the streets at night."
Most analysts agree that the militias, none of whom can decisively defeat their rivals, will not tear Libya apart just yet. People are focused on elections, scheduled for June. As with other uprisings throughout the region, the promise of a tangible barometer of democratic gain has done much to defuse tension.
But elections may have a flip side.
As Ahmed Musrati, a fighter from Misurata who laid down his weapons after the fall of Tripoli in August, said: "The people have seen a lot of blood, so elections are a big thing for us. We have to be very careful about the government we choose.
"If it's no good, I still have my guns."
Johnson is a special correspondent. Times staff writer Jeffrey Fleishman in Cairo contributed to this report.