KANANGA, Democratic Republic of Congo — They are everywhere. Here next to a house, where a woman is hanging clothes to dry. There in a field, where children are playing.

They are graves, filled with hundreds of bodies.

In the town of Nganza, in the heart of the Democratic Republic of Congo, the dead have been decomposing for months. Now it may be too late to identify them. The ground that covers them has turned almost smooth again. The only sign that there are people buried here are the government soldiers in red berets and aviator sunglasses, posted nearby with AK-47s.

They are deployed not for protection but to stop anyone from investigating witnesses’ claims that the security forces went door to door here in March, gunning whole families down in their homes and then closing the doors behind them.

The slaughter in Nganza was part of a wider conflict that has engulfed the Kasai, a region in the center of this vast country, where government forces are fighting a militia opposed to President Joseph Kabila. The violence, rooted in political and economic grievances, was ignited last August when troops killed the group’s leader, a hereditary chief who went by the name of Kamwina Nsapu (pronounced ka-MEE-na SA-poo) meaning “black ant.” His followers, many of them children, retaliated, and the conflict spread like wildfire.