The former Belgian colonial government in Rwanda had introduced the concept of ID cards for the Rwandans. These cards clearly stated whether the cardholder was a Muhutu, Mututsi, or Mutwa. This brought with it a fixed concept of group or racial identity, something that was not so prevalent so far. The post-colonial government of Rwanda decided to retain this practice, and many Hutus in the government endorsed it, too.
The systematic killings that were a feature of the Rwandan genocide were helped in a big way by this system. At the many roadblocks, which were spread all across town, it would probably have spelt certain death for someone to have been seen with an ID reading Tutsi.
At the Kigali Memorial Centre, there are a few ID cards on display. They were being carried by people who were killed during the days of the genocide and still bear the bloodstains.