If hell has an outpost on earth, it is the central prison in Giterama. For almost four years now, 7,000 men have been sleeping, standing, washing, defecating and dying beside each other, in a jail built for 700.
In windowless dungeons, emaciated prisoners lie on their bunks all day, stacked in rows like sardines in a can. The stench of faeces fills the air. There is no room to stand, or move about. The sick - malaria, TB, AIDS - sleep cheek by jowl in the same room as the healthy.
These men are accused of some of the worst crimes against humanity, committed during the 1994 genocide in Rwanda. But their treatment at the hands of a ramshackle, snail's-pace justice system is an abomination in itself.
Almost four years after the killing of 800,000 Tutsis and moderate Hutus in the genocide, hardly any of these prisoners have been tried. Meanwhile, the numbers in jail continue to grow by the day; according to the UN's human rights field operation, there are now 130,000 prisoners in jail on suspicion of crimes of genocide.
"At the rate they're dealing with these cases, it will take four centuries for the authorities to serve justice," says one human rights monitor.
The government says it lacks the resources to process the cases more quickly, but suspicions of footdragging are growing. The return of over one million refugees to Rwanda has seriously destabilised the north-west of the country; it is feared a mass release of prisoners might cause further problems.
But human rights observers also claim the regime is using the pretext of genocide crimes to lock up without trial anyone it considers undesirable.
In Giterama prison, there are new arrivals every day. The governor has run out of the distinctive pink uniforms that were doled out to every prisoner. Using tarpaulin donated by the Irish aid agency Concern, many prisoners have built makeshift shelters in the central courtyard - at least it is better than the airless dungeons. Others sleep in their thousands in the open, even when it rains. Possessions and sleeping blankets are suspended from the rafters or the walls.
As in all jails, the prisoners have established their own hierarchy. Different areas of the prison are allocated to specific activities, such as the laundry or hairdressing. Prisoners wash in public, stripped to their underpants. Meals are cooked nearby in huge oil drums, using food provided by the Red Cross.
In spite of the appalling conditions, the underground warren of passageways and rooms in the old section of the prison is home to an amazing breadth of human activity. The hospital ward is full of TB patients, but there are no medicines available.
In the assembly hall, it is Friday, the eve of the Seventh Day Adventist sabbath. The service is conducted by a pink-suited minister and prisoner. On a lower level, Catholics are praying softly; nearby, Muslim prisoners have established a makeshift mosque. At the end of the passageway, a French class is in progress.
In the governor's office, a chalk blackboard records the prison's present population - 6,945 men, 229 women and 18 children. Some 180 prisoners are teenagers.
The same blackboard reveals the slow pace of justice. Just 18 prisoners have been tried and convicted; six have been given the death sentence. The rest say they have heard nothing about their cases.
Aid from the Irish Government has been instrumental in helping to rebuild Rwanda's justice system. Many of the country's lawyers and judges were killed during the genocide, or fled after it.
Concern and Trocaire have also pitched in, helping to improve the administration of justice and to alleviate conditions for prisoners. In Giterama, for example, Concern organises a feeding programme four times a week for 9,000 prisoners in 12 cachots (village prisons).
Concern has also built a wall around the women's prison to allow the inmates the chance to get some fresh air. As part of a self-help programme, the women sell their embroidery and knitwear and spend the income on food and medicines. Literacy classes have also been organised, partly to help prisoners to understand the charges being made against them.
Income has also been generated through a pig-breeding programme staffed by male prisoners who were vets before the genocide. "If we don't support these projects, no one else will. The problem is that spending money on prisons isn't popular with the public back home," says Paul Sherlock of the agency's Giterama office.
Local courthouses have been rebuilt and stocked with basic equipment. "We're waiting, and we're ready," says Jean-Baptiste Kalindi, a local court judge, when asked when the genocide cases would be heard. However, he says he has not yet received the dossiers from the judicial investigators.
But time, and excuses, are running out for the Rwandan authorities. Even supportive governments, such as the US and Britain, have begun asking serious questions about the delays in administering justice.
In total, the Rwandans have completed 304 cases, with all but 17 defendants found guilty. Only the UN's International Criminal Tribunal on Rwanda makes this record look good. The ICTR, which sits in Arusha, Tanzania, and has been dogged by corruption and incompetence, has just three genocide trials in progress. It has not yet secured a single conviction.