Libyans struggle with secrets of mass graves
As the Libyan authorities try to secure the extradition of the former head of intelligence, Abdullah al-Senussi, the BBC has been told that there could still be as many as 8,000 missing or disappeared people in the country, from both sides of the conflict, as the BBC's Wyre Davies reports from Tripoli.
On a sandy stretch of waste ground a few miles outside Tripoli, a small crowd of militiamen gather almost excitedly around a large yellow earthmover. The digger is excavating a huge hole in the ground.
From the pile of earth at the side of the hole a few bones are sticking out. Bones that are immediately recognisable as belonging to humans: long leg bones and pieces of skull. This is a mass grave.
At this particular site, Ahmed Atar, a medical student and militia member, tells me there may be as many as 30 or 35 bodies.
"These were people killed right at the start of last year's revolution," he tells me.
"When the regime wanted to clean the streets of Tripoli, so it could show off to the foreign press how much it was in control, they shot protesters and buried their bodies here."
Search for relatives
Hisham Sharif is hoping his brother has not met a similar fate. I went back with him to En Zara prison. This is where 40-year-old Tarek was last seen after he was detained at the clinic where he worked as a doctor.
As long as there is a chance his brother may be alive, or that he can at least recover his body, Hisham will try anything and has already given a DNA sample to a central data bank.
"I don't know if he's dead or alive," Hisham says with tears in his eyes as we look over the prison courtyard, now full of captured Gaddafi loyalists. "I just need to know where Tarek is."
Later, at a small centre established to help families of the missing, I gaze at a huge wall of photographs. There are about 800 pictures, mainly of young men, but also some older men and a few women.
Crucially, they are not just opponents of the former Gaddafi regime but men in uniform and others who either supported or served the former leader.
These are some of Libya's missing - a gap on the wall indicates where a photo has been removed, not because someone has been found alive but because their body has been identified.
Officials at the organisation set up to help families of the missing said some of them had been abducted on the direct orders of Abdullah al-Senussi, Col Gaddafi's hated head of intelligence.
The Libyan government has now requested his extradition after he was reportedly detained over the weekend in neighbouring Mauritania.
To be blunt, Libya is ill-equipped to do much about the missing. Central government is alarmingly weak and ministries are barely more organised than the country's many armed militias.
Soaade Messoudi from the International Committee of the Red Cross (ICRC) says relatives of the missing should not expect too much, too soon - especially in a country with little expertise in forensics. Excavating graves with diggers is not the best way to preserve bodies or collate evidence.
"These people are so desperate that, even during the fighting, they would go to grave sites and dig up the bodies, thinking they would find their loved ones," Messoudi tells me from the base in Tripoli where the ICRC is trying to advise and help the fledgling and inexperienced Libyan authorities.
"It just isn't going to happen quickly, they have to be told this is a process that will take years."
During part of last year's uprising, much of the international media was "billeted" by the Gaddafi government at the infamous Rixos hotel in Tripoli. At night we would often hear the sound of gunfire from the woods behind the hotel.
This week my suspicions were confirmed when I was shown a video of dozens of dead bodies, lying in a ditch behind the Rixos.
They were, apparently, activists picked up from their homes in Tripoli and brought here to be executed.
By the time they were discovered many of the bodies were unidentifiable.
No-one has lost more than Abu Salam. Photographs of five smart young men, all college graduates, are spread out on the carpet in front of him. Abu Salam has not seen or heard from his sons since they were all abducted by Gaddafi's police last summer.
"One of the boys, Ahmed, was picked up when he went out walking. They beat him and forced him call his brothers for help, saying he'd been in an accident.
"They were all taken in the space of 15 minutes. It was an ambush," Abu Salam told me in the living room of a large family home that he had built with his sons.
Human rights groups say there are as many as 8,000 missing or disappeared people in Libya.
The old man keeps a lonely vigil in the hope that at least one of his boys may come home.