Some experts believe this isolation contributed to the genocide. So did poverty — both Xavier and Cecile used to live on less than a dollar a day in crowded mud huts thatched with palm fronds.

The conflict between their people dates back to colonialism, when the Belgians put Tutsis in power and Hutus to work in the fields. A Hutu regime took over at independence, and in 1994 its leaders incited Hutus to kill their Tutsi neighbors.

Xavier, a Hutu, stares at the floor as he remembers, and his small frame seems to shrink. It is hard to believe this man with the round, kind face and the thin mustache did what he did.

"We were told the Tutsis were evil and needed to be killed," he says, as the children play on the dirt floor and Cecile listens expressionless to a story she has heard before. "We really hunted for the Tutsis, searching out their hiding places and killing them wherever we found them."

The mob in Mayange killed hundreds. Cecile's Tutsi family fled to the parish church, but it was hit with tear gas and grenades. She and her mother escaped to a refugee camp in Burundi. She never saw her father, brothers or sisters again.

The anger still flares in her brown eyes when she tells the story. Her voice remains barely audible, as is considered polite in Rwandan society.

After the war, the Tutsis threw Xavier and about 120,000 other killers into jails designed to hold 20,000. There were no toilets and no room to sleep. Guards used hoses to wash prisoners, who were packed like sardines in their own filth in huge open cells.

Xavier stood in prison for 18 hours a day and longed for revenge. Most African civil wars reignite within 10 years of a cease-fire.

When Cecile returned home from Burundi, her hatred too ran deep. Even today, she can instantly switch from cheerful matron to suspicious survivor.

"Whenever I saw a Hutu child around the age of 12, I wanted to get a club and bash their skulls in because my two brothers and my two sisters were dead," she says, with the calm matter-of-factness common among genocide survivors in Rwanda, where showing emotion is frowned upon. "I would lie awake at night feeling nothing but anger and hatred."

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This burning desire for revenge is one reason peace agreements fail.

The list of African countries that slide in and out of war is long: Liberia, Sierra Leone, Sudan, Congo, Burundi, Ethiopia, Eritrea, Uganda, just to name a few. Somalia has spent the past 18 years at war, despite 14 peace agreements. In Sudan's Darfur region, neither the government nor the rebels have respected four cease-fires.